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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.
| 8251. |
A true solution of cane sugar is prepared by dissolving |
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Answer» cane SUGAR in WATER |
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| 8252. |
A true solution is |
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Answer» CLEAR and transparent |
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| 8253. |
A true covalent bond is formed by |
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Answer» TRANSFER of electron from one ATOM to the other |
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| 8254. |
A trivalent metal X is isolated by the process of electrolytic reduction. It is the most abundant metal in the earth's crust. Identify the metal and state its two uses. |
| Answer» Solution :The metal is ALUMINIUM. It is used to make cooking VESSELS, and its ALLOY is used in making AIRCRAFT. | |
| 8255. |
A thin layer of zinc is applied on the plates of steamer to prevent its rusting. |
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Answer» Solution :The plates of steamer CONSISTS of iron. After sometime, due to presence of water and dissolved oxygen, its surface get COVERED with a reddish brown flaky substance CALLED RUST. Hence, to prevent the rusting of iron, a layer of more reactive metal Zn is applied on its surface. |
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| 8256. |
A thick paste of cement, sand and water is called |
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Answer» CONCRETE |
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| 8257. |
(a) The modernperiodictablehas beenevolvedthrough the early attempts of Dobereiner, Newlandand Mendeleev. List one advantageand one limitation ofall the threeattempts. (b) Namethe scientist who firstof allshowedthat atomicnumber of an element is a more fundamentalpropertythan its atomic mass. StateModernperiodiclaw. |
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Answer» Solution :(a) Dobereiner's Triads Advantage : It was the first genuine scientific attempt to group elements with similar characteristics in traids. Limitation : The number of triads was limited to a few elements only. Therefore, this attempt could not gam IMPORTANCE. Newland's Law of Octaves Advantage : This law for the first time gave the idea of groups. Moreover, the elements were arranged in increasing order of ATOMIC MASSES. Limitation : This classification was successful only upto calcium. Mendeleev's Classification Advantage : Mendeleev's classification laid che foundation of the Modern Periodic Table. He was successful. in arranging large number of known elements into groups and periods Limitation : The basis of classification as given by Mendeleev's periodic law was not correct. This led to MANY LIMITATIONS e.g. position of hydrogen, position of isotopes etc. (a) It was given by Moseley in the form of Modern Periodic Law. (c) According to Modern Periodic Law 'physical and chemical properties of elements are the periodic function of their atomic numbers. |
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| 8258. |
(a) The modem Periodic Table has been evolved through the early attempts of Dobereiner, Newland and Mendeleev. List one advantage and one limitation of all the three attempts.' (b) Name the scientist who first of all showed that atomic number of an element is a more fundamental property than its atomic mass. (c) State Modem Periodic Law. |
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Answer» Solution :(a) Dobereiner Attempt : ADVANTAGE : The atomic mass of the middle element of the triad was the mean of the other two elements. Limitation : Dobereiner could identify only three TRIADS. Newland Attempt : Advantage : Every eighth element has properties similar to that of the first. Sodium is the eighth element after lithium. These two elements have similar properties. Limitation : Newlands law of Octaves was found to be applicable only upto calcium. After calcium, every eight element did not possess properties similar to that of the first. Mendeleev Attempt : Advantage : The elements were arranged on the basis of their fundamental property, the atomic mass and also on the similarity of CHEMICAL properties. Limitation : No FIXED position in the periodic table could be given to hydrogen by Mendeleev classification. (b) Henry MOSELEY. (c) Properties of elements are a periodic function of their atomic number. |
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| 8259. |
(a) The given diagram displays a chemical reaction. Observe carefully and answer the following questions : (b) Identify the type of chemical reaction that will place and define it. How will the colour of the salt change ? (c) Write the chemical equation of the reaction that takes place. (d) Mention one commercial use of this salt. |
| Answer» SOLUTION :For ANSWER, CONSULT SECTION 1.5. | |
| 8260. |
(a) The elements of the second period along with their atomic numbers in parentheses are given below : B (5), Be (4), O(8), N(7), Li (3), C (6), F (9) (i) Arrange them in the same order as they appear in the periodic table. (ii) Which element has the largest and smallest atom ? (b) Why does atomic radius change as we move from left to right in a period ? |
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Answer» Solution :(a) (i) Li (3), Be (4), B (5), C (6), N (7), O(8), F (9) (ii) The element Li has the largest atom. The element F has the smallest atom. ltbnrgt (b) Along a period, the nuclear CHARGE increases and the electrons are ATTRACTED more towards the nucleus. THEREFORE, the atomic size or atomic radius decreases as we move from left to the right along a period. |
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| 8261. |
(a) The boxes given here with numbers 1, 2, 3 and 4 represent a class of hydrocarbons. Write the name of first member of that respective class according to the numbers given. (b) Name the functional group in the following structures of hydrocarbon compounds and name these hydrocarbon compounds : |
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Answer» Solution :(a) (1) Methane (2) Ethyne (3) CYCLOPROPANE (4) Benzene (b) (i) CARBOXYLIC group, Butanoic acid (II) Aldehyde, Propanal |
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| 8262. |
(a) Test tube contains a brown liquid in it. The colour of the liquid remains the same when methane is passed through it but it disappears when ethene is passed. Suggest the name of the liquid brown in colour. Give the chemical equaiton involved. (b) the formula of an ester is C_(3)H_(7)COOC_(2)H_(5). Write the formulae of the acid and alcohol from which the ester is prepared. |
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Answer» Solution :(a). The brown liquid seems to be bromine dissovled in water. Methane `(CH_(4))` is a saturated hydrocarbon and does not react with bromine. Ethene `(C_(2)H_(4))` being unsaturated in nature, decolourises bromine and its colour therefore,disappears. `UNDERSET("Ethene")(CH_(2))=CH_(2)+underset(("Brown"))(Br_(2)(aq))tounderset("1,2-Dibromoethane (colourless)")(underset(Br)underset(|)(CH_(2))-underset(Br)underset(|)(CH_(2))` (b) In an ester, the LEFT side in the molecular FORMULA containing `C_(3)H_(7)CO` is derived from the acid while the right side having `OC_(2)H_(5)` is from the alcohol. this means that the aid and alcohol participating in the ester are `C_(3)H_(7)COOH and C_(2)H_(5)OH` respectively.the formation of ester may be shown as follows:  .
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| 8263. |
A test tube contains a brown coloured liquid. The colour of the liquid in test tube remains unchanged when methane is passed through it, but disappears when ethene is passed. Which element is present in the liquid? |
| Answer» SOLUTION :The ELEMENT PRESENT in the LIQUID is BROMINE. | |
| 8264. |
A teacher while explaining the definition of ionisationn potential gave an example: Ionisation potential value of sodium is 140 kJ// mol. That means, 140 kJ of energy is required to remove the lone electrons form '3s' orvitals of one mole of gaseous sodium atoms. Then, a student Rinku stood up immediately and asked: sodium is a solid metal. Why should we consider it in gaseous state? What explanation would have been given by the teacher? |
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Answer» Solution :For any element. Ionisation potential is considered for gaseous state only. Ionisation potential corresponds to the energy required to overcome the electron WITHOUT considering any other kinds of attreactions. In gaseous state, the intermolecular FORCES of attractions being negligible, removal of electron from a neytrak gaseous atom involces an amount of energy equal to IP only. In solid and liquid states, the intermolecular forces of ATTRACTION are STRONGER ant the energy required to remove electron involves not only IP but also the energy required to overcome the other forces. Thus, for any element, IP is considered only for the isolated gaseous atoms irrespective of the state in which it EXISTS. |
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| 8265. |
A tall plant with red flowers (TrRr) is self pollinated. Represent the plants obtained in F_2generation with the help of a checker board (Punnet square). The traits which are not found in the parental plants are expressed in the offspring. Why? |
Answer» Solution : PR:9:3:3:1 GR:1:2:2:4:1:2:1:2:1 ii) Due to VARIATION (MIXING up of GENES) new TRAITS are formed. |
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| 8266. |
A system suffers an increase in internal energy of 80J and at the same time has 50J of work done on it. What is the heat change of the system? |
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Answer» `+130J` |
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| 8267. |
A symbol of an element represents |
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Answer» one ATOM of the ELEMENT |
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| 8268. |
A suspension is |
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Answer» HOMOGENEOUS. |
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| 8269. |
The pH of a salt used to make tasty and cripsy pakoras is 14. Identify the salt and write a chemical equation for its formation. List it's two uses. |
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Answer» Solution :The substance which is used for making DIFFERENT shapes is PLASTER of Paris. Its chemical name is calcium sulphate hemihydrate `(CaSO_(4).½H_(2)O)`. The two FORMULA unit of `CaSO_(4)` share ONE molecule of water. As a result, it is soft. When it is left open for some time, it absorbs moisture from the atmospere and forms gypsum, which is a hard solid mass.. `underset("(Sulphate salt)")underset("(Soft)")underset("Plaster of Paris")(CaSO_(4). ½H_(2)O + 1½ H_(2)O) rarrunderset("(Hard mass)")underset("Gypsum")(CaSO_(4).2H_(2)O)` |
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| 8270. |
A sulphate salf of Group 2 element of the Periodic Table is a white , soft substance , which can be moulded into different shapes by making its dough . When this compound is left in open for some time, it becomes a solid mass and cannot be used for moulding purposes Identify the sulphate salt and state , why does it show such a behaviour . Give the reaction involved. |
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Answer» Solution :The substance which is used for making different shapes is Plaster of Paris . Its chemical name is calcium sulphate HEMIHYDRATE `(CaSO_(4).1//2H_(2)O)`. The two formula UNIT of `CaSO_4` share one molecule of water . As a result, it is soft. When it is left open for some time. it absorbs moisture from the ATMOSPHERE and FORMS gypsum, which is a hard SOLID mass. `underset(("Sulphate salt"))underset(("Soft"))underset("Plaster of Pairs")(CaSO_(4).1/2H_(2)O)+1(1)/(2)H_(2)Orarrunderset(("Hard mass"))underset("Gypusm")(CaSO_(4).2H_(2)O` |
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| 8271. |
A substance X which is an oxide of a metal is used intensively in the cement industry. This element is present in bones also. On treatment with water it forms a solution which turns red litmus blue. Identify X and also write the chemical reactions involved. |
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Answer» Solution :The substance X is calcium oxide, CAO. The element calcium is PRESENT in bones. On treatment with water, it produces calcium hydroxide as under: `CaO + H_2O + CA(OH)_2` Calcium hydroxide is a base. It turns red LITMUS blue. |
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| 8272. |
A substance Xused for coating iron articles is added to a blue solution of a raddish brown metal Y, the colour of the solution gets discharged. The type of reaction. |
| Answer» SOLUTION :TYPE of REACTION is DISPLACEMENT reaction | |
| 8273. |
A substance Xused for coating iron articles is added to a blue solution of a raddish brown metal Y, the colour of the solution gets discharged. Identify X and Y |
| Answer» SOLUTION :X is FE, Y is CU | |
| 8274. |
A substance that gains electron(s) is |
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Answer» an OXIDISING AGENT |
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| 8276. |
(a) Study the following chemical equation: CaSO_4. 2H_2O to^(373 K) CaSO_4. 1/2 H_2O+3/2 H_2O Name the reactant and the product and mention one use of the product. (b) The following salts are formed by the reaction of an acid with a base: (i) Sodium chloride (ii) Ammonium nitrate Identify the acid and the base and tabulate your answer in the format given below: |
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Answer» SOLUTION :(a) Reactant : GYPSUM Product: Plaster of paris USE: As plaster for SUPPORTING the fractured BONES . 
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| 8277. |
A student was given two metal strips X and Y alongwith colourless nitrate solution to perform two separate displacement reactions. When the student placed metal strip X in nitrate solution for a considerable time he observed hat the solution turned blue and coating of silver meal was formed on the strip. And when the student immersed meal strip Y in silver nitrate solution for an equal time, the observed that the solution turned light green with the fomation of a coating of silver meal on the strip. The correct conclusion of the student about the identity of meals X and Y is: |
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Answer» `X` is copper and `Y` is MAGNESIUM |
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| 8278. |
A student wants to study the decomposition reaction of iron sulphate in laboratory. What care the student should take and why ? |
| Answer» Solution :The student should wear lab coat, hand gloves and safety goggles because heating of test tube containing iron sulphate may cause BURN, Moreover sulphur dioxide gas released during decomposition of iron sulphate has strong chocking SMELL. HENCE, the student should use mask and keep the exhaust FAN on in the laboratory. | |
| 8279. |
A student tests a sample of drinking water and reports its pH as 6 at room temperature. Which one of the following might have been added in water? |
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Answer» WASHING soda |
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| 8280. |
A student test the pH of pure water using a pH paper .It shows green colouro.If a pH paper is after adding lemon juice to water,What colour will he observe? |
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Answer» Green |
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| 8281. |
A student takes three beakers A,B and C filled with aqueous solution of glucose, alcohol and hydrochloric acid respectively as shown in the following figure. (i) State your observations in terms of glowing of bulb when the switch is on. (ii) Justify your observations by giving reason in each case. (iii) Mention the change noticed with appropriate reason if the content of beaker B is replaced by sodium hydroxide solution. |
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Answer» SOLUTION :(i) Bulb A and B do not glow but bulb C glow. (ii) Glucose and alcohol solutions do not conduct electricity as they do not have ions. Dil. HCl contains ions so the flow of ions is responsible for the flow of current. (iii) After replacement, bulb glows in B as NaOH solution contains ions `(NA^+ and OH^(-) ions)` |
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| 8282. |
A student put the spatula of iron in the test tube containing copper sulphate while performing an experiment in the laboratory. What will he observe next day? |
| Answer» Solution : The STUDENT will observe that the blue COLOURED solution of copper sulphate turns to green and the IRON SPATULA GETS the coating of brown colour metal on it, only on the surface which is dipped in the solution | |
| 8283. |
A student prepares aqueous solutions of the following salts: Copper sulphate, ferrous sulphate, sodium sulphate, barium chloride. Write the colour of each solutionthus formed. |
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Answer» SOLUTION :Copper SULPHATE : Blue Ferrous sulphate : PALE green Sodium suphate : Milky WHITE |
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| 8284. |
A student prepared solution of (i) acid and (ii) base in two separate beakers but forgot to table the solution and litmus paper is not available in the lab. Since both solution are colourless how will you distinguish between there using (a) phenolphthalein (b) methyl orange. |
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Answer» Solution :(a) When we add phenolphthalein to acid it will be COLOURLESS. When we add phenolphalein to base, it burns pink. (B) When we add METHYL ORANGE to acid it turns red. When we add methyl orange to base it turns yellow. |
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| 8285. |
A student prepared 20% NaOH solution in a beaker containg water. The observation made by him are as follows : (i) NaOH are in the form of pellets. (ii) It dissolves readily in water. (iii) The beaker appears cold from outside. (iv) Red litmus paper turns blue when dipped in the solution. The correct observation are : |
| Answer» Solution :i,ii and iv | |
| 8286. |
A student places a piece of cucumber a glass piece, a banana peel and a plastic pen in a pit and closes it. What changes can be observed in these materials after a month ? Give scientific reason for these changes. |
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Answer» SOLUTION :CUCUMBER piece and banana pccl are orgaine subst.anees. They are biodegradalble SUBSTANCES, and are eeofriendly. Giass piece ad plastic pen arc morganic SYNTHETIE substauces. They are non-biodegradable substances and CAUSE soil pollution. |
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| 8287. |
A student has mixed the solution of lead (II) nitrate and potassium iodide. Write a balanced chemical equation for the reaction. |
| Answer» SOLUTION :`PB(NO_(3))_(2)(AQ.)+2Kl(aq.)toPbl_(2)(aq.)+2KNO_(3)(aq.)`. | |
| 8288. |
A student has difficulty reading the blackboard while sitting in the last row. What could be the defect the child is suffering from? How can it be corrected? |
| Answer» Solution :The student is suffering from MYOPIA or SHORT sightdness. The defect can be CORRECTED by the use of convcave LENS of SUITABLE power | |
| 8289. |
A student has mixed the solution of lead (II) nitrate and potassium iodide. Suggest an alternative name for the above precipitation reaction. Give justification for your answer. |
| Answer» SOLUTION :Double-displacement reaction, SINCE there is a mutual exchange of radicals between the REACTANTS. | |
| 8290. |
A student finds the pH of a sample of vegetable soup was 6.5. How is this soup likely to taste ? |
| Answer» SOLUTION :The taste will be SLIGHTLY SOUR as it is weakly ACIDIC. | |
| 8291. |
A student dropped a few pieces of marble in dilute hydrochloric acid, contained in a test tube, the evolved gas was then passed for a long time through lime water. What changes would be observed in lime water ? Write balanced equations for both the changes observed. |
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Answer» Solution :On adding pieces of MARBLE is the test tube containing dil. HCl a brisk evolution of `CO_(2)` takes palce. Carbon dioxide when passed through lime water turns it milky because of the FORMATION of insolube calcium carbonate. `CaCO_(3)(s) +2HCl (aq) rarr CaCl_(2)(aq) + CO_(2)(g) +H_(2)O(l)` `UNDERSET("Lime water")(Ca(OH)_2) + CO_2 rarr underset("(milky)")underset("carbonate")underset("Calcium")(CaCO_3 + H_(2)O` (II) If `CO_2` is continuosly passed for a long time , the milkiness disappears due to the formation of soluble sodium hydrogencarbonate. `CaCO_(3)+CO_(2)+H_(2)O rarr underset("saluble")(Ca(HCO_3))_2` |
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| 8292. |
A student dropped a few pieces of marble chips in dilute hydrochloric acid contained in a test tube. The gas evolved was passed through lime water. What changes would be observed lime water ? Write the chemical equations for both the changes observed. |
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Answer» Solution :On passing carbon dioxide through lime water, initially a precipitate of calcium carbonate is formed and on passing excess of carbon cioxide the calcium carbonate is reduced to calcium bicarbonate, which is SOLUBLE in aqueous medium , hence the solution BECOMES COLOURLESS. `Ca(OH)_(2)(aq.)+CO_(2)(g)toCaCO_(3)(s)+H_(2)O(l)` `CaCO_(3)(s)+CO_(2)(g)+H_(2)O(l) toCa(HCO_(3))_(2)(aq.)`. |
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| 8293. |
A student connects a water heater toa 5A electric ciruit. Is this correct? Give suitable reason to your answer. |
| Answer» SOLUTION :No, this is not correct. WATER heater consumes LARGE AMOUNT of energy. Connection with a low energy circuit can cause short circuit and overloading. | |
| 8294. |
A student burnt a metal A found in the forrn of ribbon. The ribbon burnt with a dazzling flame and a white powder B is formed which is basic in nature. Mg+O_2-2MgO |
| Answer» SOLUTION :`Mg+O_2-2MgO` | |
| 8295. |
A student burnt a metal A found in the forrn of ribbon. The ribbon burnt with a dazzling flame and a white powder B is formed which is basic in nature. IdentifyA and B |
| Answer» SOLUTION :A is MGB is MGO | |
| 8296. |
A student adds a spoon full of powdered sodium hydrogen carbonate to a flask containing ethanoic acid. List two main observations he must note in his note book, about the reaction that takes place. Also write chemical equaiton for the reaction. |
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Answer» Solution :The TWO main observations are : (a) Brisk effervescence of a gas that TURNS lime water milky. The gas released is `CO_(2)`. (b) it is a neutralisation reaction RELEASING salt, water, `CO_(2)` and heat. `CH_(3)COOH(aq) + NaHCO_(3)(s) rarr CH_(3)COONA(aq) + CO_(2)(g) + H_(2)O(l)` |
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| 8297. |
A student addd few pieces of aluminium metal to two test tubes A and B containingaqueoussolutions of ironsulphateand copper sulphate. In the second part ofher experiment, the added iron metal to anothertest tubes C and D containing aqueoussolutions of aluminium sulphateand copper sulphate. In which test tube ortest tubeswill sheobservecolourchange? On the basis of this experiment, statewhich one is the most reactivemetal and why ? |
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Answer» Solution :The chemical reactions involved in all the FOUR TUBES are listed. `"Test tube A : "underset("(Lightgreen)")(3FeSO_(4)(aq))+2Al(s)rarrunderset("(COLOURLESS)")(Al_(2)(SO_(4))_(3)(aq))+3Fe(s)` `"Test tube B : "underset("(Blue)")(3CuSO_(4)(aq))+2Al(s)rarrunderset("(Colourless)")(Al_(2)(SO_(4))_(3)(aq))+3Cu(s)` `"Test tube C : "underset("(Colouless)")(Al_(2)(SO_(4))_(3)(aq))+Fe(s)rarrunderset("(No colour change)")("No chemical reaction")` `"Test tube D : "underset("(Blue)")(Cu(SO_(4))(aq))+Fe(s)rarrunderset("(No colour change)")(FeSO_(4)(s)+Cu(s))` Change of colour will be OBSERVED in test tubes A, B, and D while the solution will remain colourless in test tube C. On the basis of the chemical reactions, listed above, Aluminium (Al) is the most reactive metal because it has displaced all other metals from their aqueous salt solutions. |
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| 8298. |
A strongly acidic solution is taken and a base is slowly added to it drop by drop. Arrange the colours observed during the process of addition in proper sequence. {:((1) " green",(2) " indigo"),((3) " orange",(4) " red"),((5) " blue",(6) " violet"),((7) " yellow",):} |
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Answer» 3 4 1 7 2 5 6 (iv) GREEN (v) blue (VI) indigo (vii) violet |
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| 8299. |
A strong electrolyte and a week electrolyte . |
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Answer» Solution :(i) A strong ELECTROLYTE is completely ionised whereas a weak electrolyte is only partically ionised in aqueous solution. (II) The conductivity of a strong electrolyte is very HIGH , whereas the conductivity of a weak electrolyte is low . |
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| 8300. |
A strong alkali forms an acidic salt with a dibasicacid. From the aqueous solution of the salt formed on the addition of dilute acid evolves a gas that turns lime water milky. Identify the salt and predict the reactions involved in it |
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Answer» Solution :(i) gas that TURNS lime water MILKY (ii) IDENTIFICATION of gas (iii) dibasic acid RESPONSIBLE to PRODUCE this gas (iv) acidity of the alkali (v) requisite for acidic salt |
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