InterviewSolution
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InterviewSolution
This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.
| 2101. |
Match the following :{:(A,B),("Hydrogen",(a)oplus),("carbon",(b)odot ),("copper",(c )lambda),("phosphorus",(d) •):} |
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| 2102. |
{:("A","B"),("1) Temperature","a) Kilogram per cubic meter"),("2) Weight","b) Pascal"),("3) Volume", "c) Kelvin"),("4) Density", "d) Newton"),("5) Pressure", "e) Cubic meter"):} |
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| 2103. |
ExplainColloid with example ? |
| Answer» SOLUTION :Homogenoussoultionin whichsolute Particlesare bigger thantrue solution. Example :-Ink, BLOOD ,MILK . | |
| 2104. |
A,B and D are four 9th class students .Their chemistry teacher conducted rrole play in the classwhich is as given below she assumed that a is a metal andbn is anon metal c and d needto carry out two separte experiments for this purpose c needs and ocxidaing agent and d needs a reducing agent accordingly they have to form two goupsconsisting of two students each how will they form the group? explain this with appropriate reasons |
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Answer» Solution :Oxidizing AGENT is the substacne which not only oxidis othe substance but also undergoes reduction by itselg i.e it accepts electons form the others .The more the NON metallic acharcter of an element the more is its tendency to accept electons and thus acting as a good oxidizing agent Reducing agent is the substance which REDUCES the other susbtaces but itslf undergoes oxidation that means it gives up its electrons The more hte metallic CHARACTER the more is the tendency of losing electrons hence metals are good reducing AGENTS the poiring should be aand d andb adn c |
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| 2105. |
Explain carbon cycle or biogeochemical cycle. |
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Answer» Solution :The carbon CYCLE is a biogeochemical cycle by which carbon is exchanged among the biosphere, geosphere, hydrosphere and atmosphere of the Earth. Carbon is the main component of biological compounds as well as major component of many MINERALS such as lime stone. Steps in carbon cycle: 1. Carbon enters the atmosphere as `CO_(2)` from respiration and combustion. 2. `CO_(2)` is absorbed by producers to make carbohydrates in photosynthesis. 3. Animals feed on the plant passing the carbon compounds along the food chain. Most of the carbon they consume is exhaled as `CO_(2)` formed during respiration. The animals and plants eventually die. 4. The DEAD ORGANISMS are eaten by decomposers and the carbon in their bodies is returned to the atmosphere as `CO_(2)`. The plant and animal material may then be available as fossil fuel in the future for combustion. 
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| 2106. |
Expalin with equation how sulphur dioxide is prepared in the laboratory. |
| Answer» SOLUTION :N/A | |
| 2107. |
It is a hot summer day. Priyanshi and Ali are wearing cotton and nylon clothes respectively. Who do you think would be more comfortable and why ? |
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Answer» Solution :(a) (i) Squeeze the shirt with force. By doing so, some of the moisture is removed. (ii) Spread the shirt on a stand. It provides greater surface AREA for evaporation. (iii) Iron the shirt. INCREASE in temperature helps in DRYING the shirt. (b) Cotton clothes WOULD be more comfortable than the nylon clothes since these are porous. Perspiration sticking to the SKIN can escape from the pores. Priyanshi would feel more comfortable. |
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| 2108. |
Excessiveuse of chemical fertilizers reduces soil fertilityin the long run . |
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| 2109. |
(a) You are given an elemetn ""_(7)^(14)X.Find out (i) number of protons, elecirons andneutrons in X. (ii) valency of X (iii) electronic configuration of X. (b)If bromine atom in the form of, say two isotopes " "_(35)^(79) Br (49.7%) and " "_(35)^(81)Br (50.3%). Calculate the average atomic mass of bromine atom. |
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Answer» Solution :(a) The atomic number of X : 7 (1) Number of protons : 7 Number of neutrons : 7 (ii) VALENCY of X : 3 (III) Electronic configuration : 2, 5 |
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| 2111. |
Give reasons. A wooden table should be called a solid. |
| Answer» Solution :Solids are RIGID, incompressible and have definite shape and volume. Since the table has all the above mentioned properties, therefore, it is a SOLID | |
| 2113. |
(a) Why is crystallisation technique better than evaporation ? (b) Write any two physical properties each of metals and non-metals. (c ) Name the technique used to separate butter from curd. |
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Answer» Solution :(a) Both these techniques are used to separate the solid substances from their SOLUTIONS. But crystallisation is considered BETTER because during evaporation certain solids may decompose or some of them like sugar get charred when the solution is evaporated completely to dryness. As a result of crystallisation, even the shapes of the crystals donot change. (b) (i) METALS have a shining surface known as lustre. (ii) Metals are malleable and ductile. (iii) Non-metals are mostly poor conductors of electricity. (iv) Non-metals are generally soft. (C ) Butter can be separated from curd by the process of centrifugation. This is USUALLY done by churning which is very common as well as convenient. |
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| 2114. |
Evaporation takes place from the ……….. of the liquid, while boiling takes place from the …….. of the liquid. |
| Answer» SOLUTION :SURFACE, BULK | |
| 2115. |
(a) Why does not the atomic mass of an element represent the actual mass of its atom? (b) The atomic mass of an element is in fraction. What does it mean? (c) Why is the value of Avogadros number 6.022 xx 10^(23) and not any other value? (d Does one gram mole of a gas occupy 24.4 L under all conditions of temperature and pressure? |
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Answer» Solution :(a) Atoms of diffterent ELEMENTS are very Stmal in sze and their actual mass are extremely small. For example. the mass of an atom of hydrogen is `1.67 XX 10^(-27)kg`. To solve this problem, we consider the relative atomic masses of the elements. The relative atomic mas of hydrogen is u and its corresponding gram atomic mass is 1 . If the atomic mass of an element is in FRACTION, this means that it exists in the form of isotopes. (c )It represents the number of atoms one gram atom of an element or the number of MOLECULES in divide the atomic mass of an clement by actual mass of its atoms, the `10^(23)`. Similarly, by dividing the molecular mass of a compound by the actual mass of its molecules, the same result is obtained. |
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| 2116. |
Evaporation causes cooling. |
| Answer» SOLUTION :In an OPEN vessel,theliquid keeps on evaporatiog. The particles liquid absorb energy from the SURROUNDING to regain the energy lost during evaporation. HENCE evaporation causes COOLING. | |
| 2117. |
(a) why are the chemical properties of the isotopes same? (b) Draw bohr model helium atom. |
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Answer» SOLUTION :(a) Isotoos have the same ATOMIC number as well as the same ELECTRONIC configuration .Thererfore their CHEMICAL PROPERITES are the same (b) for answer consull section4.9 (c ) 
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| 2118. |
Evaporation and Boiling. |
Answer» SOLUTION : 
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| 2119. |
(a) Which of the following species has 18 electrons ?Ca^(2+), K^(+), Cl^(-) . Ar (b) Chemial properties of all isotopes of an element are similar. State reason. |
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Answer» SOLUTION :(a) ARGON - Ar has 18 electrons. (b) Isotopes of an element have the same ATOMIC numbers but different mass numbers. The chemical properties of an element depends UPON the valence electrons. Isotopes of an element have the same number of valence electrons in their outermost orbit. Therefore, isotopes of an element SHOW similar chemtcal propertles. |
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| 2120. |
Evaporation. |
| Answer» SOLUTION :The PHENOMENON of changing of a liquid into vapour at any temperature below its BOILING point is CALLED EVAPORATION. | |
| 2121. |
(a) When common salt is added to water, will there be any change in volume ? Give reason. (b) Write any one similarity between three states of matter. |
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Answer» Solution :(a) No, there will be no change in VOLUME. The particles of common salt will occupy inter particle empty SPACES present in the molecules of water. (B) All the THREE states of MATTER consist of particles which have specific mass. |
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| 2122. |
Evaluate the Mendeleev's periodic table and find the following. Total number of periods |
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| 2123. |
Evaluate the Mendeleev's periodic table and find the following. Total number of Groups |
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| 2124. |
(a) What type of mixture is an alloy? Why? (b) A solution is always a liquid. Comment, ( c) Can a solution be heterogeneous ? |
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Answer» Solution :(a) An alloy is a HOMOGENEOUS mixture. The constituents have a uniform composition throughout. (b) A solution is not always a liquid. Solid solutions and GASEOUS solutions are ALSO possible. Bronze is a solid in solid solution. Atmospheric air is a gas in gas solution. ( c) No. A solution is always a homogeneous mixture. |
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| 2125. |
(a) What is the reason for the existence of the three states of matter ? (b) What will happen when solid ammonium chloride is heated ? (c ) The room temperature is 25^(@)C. What is the corresponding temperature on the Kelvin scale ? (d) What happens to the particle motion if the temperature of the gas is increased ? (e ) A substance 'X' was highly compressible and could be easily liquified. It could also take up the shape of any container. Predict the nature of the substance. Enlist four properties of this state of matter. |
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Answer» Solution :(a) The three states of matter differ with respect to the inter particles spaces. These are minimum in the solid state while MAXIMUM in the gaseous state. (b) It will directly change to the vapour state without passing through the liquid state. The process is known as sublimation. (C ) KELVIN temperature (K)=273+25=298 K. (d ) With the increase in temperature, the average KINETIC energy of the particles increases. As a result, the particle MOTION increases. (e ) The substance 'X' appears to be a gas since the characteristics shown by it resemble those of the gaseous state. For the properties of the gaseous state, consult section 1.3. |
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| 2126. |
Evaluate the Mendeleev's periodic table and find the following. Are the same elements showing similar properties arranged in the same group or same period? |
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| 2127. |
(a) What are cathode rays ? What is the nature of charge on cathode rays ? (b) Explain how, cathode rays are formed from the gas taken in the discharge tube (c) What conclusion is obtained from the fact that all the gases form cathode rays ? |
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| 2129. |
(a) 'Water is considered as a compound of hydrogen and oxygen and not a mixture of hydrogen and oxygen'. Comment on it. (b) Differentiate between a compound and a mixture (any three points). |
| Answer» Solution :(a) The PROPERTIES of water are altogether different from those of the constituting GASES. For example, water is a LIQUID at room temperature whereas the constituents are in the gaseous state. Water can extinguish FIRE whereas hydrogen is COMBUSTIBLE in nature, oxygen supports combustion. | |
| 2130. |
Equilibrium of the reaction of formation of hydrogen iodide from hydrogen and iodine is disturbed. The graph obtained is given below. How can you apply Le Chatelier's principle to the equilibrium and explain the graph ? |
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Answer» SOLUTION :(i) equilibrium position (ii) comparison of the CONCENTRATION of COMPONENTS before the change in concentration of `H_(2)` (iii) sudden change in the concentration of `H_(2)` (IV) comparison of the change in concentration of `H_(2)` (V) effect of the change in concentration on the equilibrium. |
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| 2131. |
Equilibrium concentration of SO_(2)Cl_(2) formed from 3 moles of SO_(2) and 4 moles of Cl_(2) present in a litre flask is 1.5 mole/L. Calculate K_(c ). |
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Answer» SOLUTION :`SO_(2)+Cl_(2) hArr SO_(2)Cl_(2)` `{:("Initial NO. of moles",3,4,0),("At equilibrium",,3-x,4-x x):}` Concentration of `SO_(2)Cl_(2)` at equilibrium is 1.5 moles. x=1.5 moles/L Concentration of `SO_(2)` at equilibrium =3-1.5=1.5 moles/L `therefore K_(c )=([SO_(2)Cl_(2)])/([SO_(2)][Cl_(2)])=(1.5)/(1.5xx2.5)=0.4 " mole" // L` |
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| 2132. |
(a) In which category of mixtures will you classify alloys and why ? (b) A solution is always a gas or liquid or solid. Comment. (c )A solution be homogeneous or heterogeneous ? |
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Answer» Solution :(a) ALLOYS are regarded as homogeneous MIXTURES SINCE the constituting elements are uniformly mixed in an alloy. (b) This statement is not true. There MAY also be solid solution (solid acts as solvent) and gaseous solutions (gas acts as solvent). (c ) No, a solution is always a homogeneous mixture of two or more substances. |
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| 2133. |
(a) Two students Ramesh and Alka were required to prepare 10 percent (mass/mass) solution chloride in water. For that, Ramesh dissolved 10 g of the salt in 100g of water while Alka dissolved 10g of the salt in water to make 100g of the solution. Which out of the two prepared the correct solution ? (b) You are given a solution of a substance 'A'. How will you test whether it is saturated or unsaturated with respect to 'A' at a given temperature ? |
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Answer» Solution :(a) Alka prepared the correct solution because by definition 10 percent solution of a SUBSTANCE means a solution containing 10g of the solute dissolved in 100g of it. This means that the mass of water in the solution is 90 g. (b) Take the GIVEN solution in a beaker. Now add SMALL amount of 'A' to this solution and stir with a glass rod. If it dissolves in this solution, this means that the solution is unsaturated. If it does not dissolve and SEPARATES as a solid at the bottom of the beaker, the solution is saturated in NATURE. |
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| 2134. |
Energy possessed by molecules resulting in effective collisions is called ____. |
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| 2135. |
Energy of the electron in the atom is negative. Explain. |
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Answer» Solution :(i) COMPARING energy of free ELECTRON and energy of electron in an atom (ii) CHANGE in energy when an electron is BROUGHT closer to the atom. (iii) REASON for the chagne in the energy of an electron. |
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| 2136. |
(a) To make a saturated solution, 36 g of sodium chloride is dissolved in 100 g of water at 293 K. Find the concentration at this temperature.(b) What is the effect of temperature on the solubility of a solid in a liquid ? (c ) Why is it possible to distinguish the particles of a solute from those of a solvent in a suspension ? |
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Answer» Solution :(a) Mass of SOLUTE = 36 g Mass = solution = (36 + 100) = 136 g Concentration of solution = `((36 g))/((136g)) xx 100` = 26.4% (b) Solubility of a solid in a liquid is generally directly proportional to the temperature. If the temperature increases, the solubility increases. If the temperature decreases, so is the solubility. However, there are some EXCEPTIONS also. Solubility of lithium carbonate in water decrease with increase in temperature. (C ) In a suspension, the size of the PARTICLES of the particles of the dispersed phase is quite big. They can be easily distinguished from the particles of the dispersion MEDIUM. They can be seen even with naked eye. |
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| 2137. |
(a) The solubility of sodium chloride in water increases with rise in temperature while that of lithium carbonate decreases. Assign reason. (b) Water containing 88.8% oxygen and 11.2% hydrogen is often used as a fire extinguisher. Can a mixture containing the two gases in the same ratio by mass be used for extinguishing fire ?(c ) The melting point of a solid when determined experimentally comes out to be 160^(@)C. But its actual melting point as given in standard books is 150^(@)C. Predict the nature of the solid. |
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Answer» Solution :(a) When SODIUM chloride is dissolved in water, the process is endothermic in NATURE. This means that heat energy is absorbed in the process. THEREFORE, solubility increases with rise in the temperature. In case of lithium carbonate, the process of dissolution is exothermic. This means that heat is evolved in the process. Therefore, its solubility in water decreases with rise in temperature. (b) No, it cannot be used. Actually, in water the two elements are chemically combined with each other. They therefore, lose their identify. But in the mixture, no chemical combination between hydrogen and oxygen has taken place. Even water cannot be formed on mixing the gases. Therefore, the mixture does not extinguish any FIRE. (c ) Since the experimentally determined melting POINT of the solid is more than the standard value of the melting point, this means that the solid is not in pure state. It has some impurities present. Please note that the purity of a solid can be determined by finding its melting point and comparing it with the standard value. |
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| 2138. |
Elements with stable electronic configurations have eight electrons in their valence shell. They are.............. |
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Answer» HALOGENS |
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| 2139. |
(a) The elements are identified by their atomic numbers and not by their mass number. Justify the statement. (b) State the rules followed for writing the number of electrons in different energy levels. |
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Answer» Solution :(a) Elements are characterlised by their atomic numbers, i.e.. the number of protons in the nucleus. The mass number of an element is the sum of the number of protons and neutrons. Atoms of the same element may have diferent mass number but their atomic number remains the same. For example, chlorine has two types of atoms `""_(17)^(35)Cl and " "_(17)^(37)`Cl. Both have the same number of protons in their nuclei, but mass numberof protons in their nuclel. but mass number is DIFFERENT. (b) The MAXIMUM number of electrons present in a shell is glven by the formula `2n^(2)`. Here, n is the ORBIT number or ENERGY level. The maximum number of electrons that can be accommodated in the outermost orbit is 8. |
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| 2140. |
A tarnished silver rod when kept in water containing magnesium bars regains its lustre. Justify. |
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Answer» Solution :(i) COMPARISION of reactivityof Ag and Mg (II) CONDITIONS required for the ions to get DISPLACED. |
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| 2141. |
Elements with higher electronegativity are good oxidizing agents .Give reasons |
| Answer» Solution :Elements with higher ELECTRONEGATIVITY have greater tendencyto attract the shared pair of electorns PRESENT in a compound .An atom which undergoes REDUCTION is and OXIDIZING agent .The greater the electronegativity value the more is its tendency to undergo REDUCTON .So it acts as a good oxidizing agent | |
| 2142. |
(a) Tabulate the differences in the characteristics of states of matter. (b) Comment upon the following: rigidity. Compressibility. Fluidity. Filling a gas container, shape, kinetic energy and density. |
Answer» Solution :(a) The main differences in the characteristics of the three states of matter, solids, liquids and gases are GIVEN below : (b)(i)Rigidity. Rigidity refers to the property of a solid to resist change in its shape (or resist deformation)when an outside force is applied. In most simple terms, rigidity means 'stiffness'. The particles in a solid are very closely packed and there are very strong forces of attraction between them, so solids posses high rigidity. Liquids and gases are not rigid because the positions of their particles are not fixed. (ii)Compressibility. Compressibility is the property of a fluid (or a solid) due to which its volume decreases when pressure is applied. The particles in gases have large spaces betweenthem due to which their volume decrease too much when pressure is applied on them. So, gases have high compressibility. On the other hand , the particles in solids and liquids are closely packed, so solids and liquids do not have much compressibility. (iii) Fluidity. The property of flowing easily is called fluidity. Gases and liquids exhibit the property of fluidity, so they are called fluids. Due to large interparticles distance and very weak forces of attraction, gases can flow EXTREMELY easily. So, the gases have very high fluidity. And because of comparatively SMALLER interparticle distances and stronger forces of attraction between their particles, the fluidity of liquids is LESS than that of gases. Solids are not fluids, they have no fluidity. (iv) Filling a gas container. A gas fills its container completely because due to high kinetic energy and negligible interparticles forces of attraction, the particles in a gas move with high speeds in all directions and occupy all the space in the container. (v) Shape. The external form or appearance of a substance is called its shape. A solid has a fixed shape because the particles in a solid are closely packed and their positions are fixed due to strong forces of attraction between them. The liquids and gases do nothave fixed shapes because the positions of particles in them are not fixed due to comparatively weaker forces of attraction between them. (vi) Kinetic energy. The energy possessed by a material due to the motion of its particles is called kinetic energy. At a given temperature, the particles in a gas have the maximum kinetic energy because they move with high speeds due to weakestforces of attraction among them. Liquids have lesser kinetic energy (than gases) whereas solids have the the least kinetic energy at a given temperature. (vii) Density. The mass per unit volume of a material is called its density. Solids have high densities because their particles are very close together. Liquids have usually lower densities than solids because their particles are somewhat more loosely packed than that in solids. Gases have the lowest densities because their particles are very far APART from one another. |
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| 2143. |
Elements with more non metallic character are good oxidizing agents and those with moree electopsotive charcter are good reducing agenets expain. |
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Answer» Solution :(i) NATURE of METAL and non metals (II) oxidizing agent and reducing agnet in terms of electronic concept (iii) relation between metals non metals oxidizing and reducing AGENTS |
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| 2144. |
a. Tabulate the difference in the characteristics of states of matter. |
Answer» SOLUTION :
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| 2145. |
Elements in the modern periodic table are arranged in ………… groups and ……………. Periods. |
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Answer» 7, 18 |
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| 2146. |
A survey showed that one time use plastic items were among the top 10 plastic items found in garbage washed up from oceans. Can this be true? Explain how. |
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Answer» Solution :Use and throwaway plastics cause short and long TIME ENVIRONMENTAL damage. These items like plastic carry bags, straws, plates, SPOONS, pouches, etc., take a few seconds to be made in a FACTORY, but can stay in the environment forever a 1000 years. These items block drains and pollute water bodies. These plastics break down into PIECES that are smaller than 5 mm in diameter. These microplastics pollute the ocean and harm the marine life, who mistake them as their food. These one time use plastics when disposed carelessly are carried to the ocean by winds, cause harm to marine life and are brought back to the shore by waves. |
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| 2147. |
A substance is said to be a solid when itsmeltingpoint lies below the room temperatureat the normal pressure . |
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| 2148. |
Elements having the same number of valence electrons in their atoms have similar |
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Answer» COMBINING capacities |
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| 2149. |
A substance has a definite composition. |
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| 2150. |
Elements and compounds are c onsidered to be ________ substances, as they contain only one kind of particles. |
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