Explore topic-wise InterviewSolutions in Current Affairs.

Neutralisation type of reaction happens between an acid and a base.

When 6 molecules of carbon dioxide and 6 molecules of water react together glucose is formed with the evolution of oxygen gas.

6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O_2.

The reaction in which more reactive metal displaces (takes place of) the less reactive metal from its compound, is called as displacement reaction. 

e.g., Fe + CuSO₄ → FeSO₄ + Cu 

It is different from double displacement reaction because in double displacement reaction two different elements or atoms or ions are exchanged for each other, 

e.g., Na₂SO₄ + BaCl₂ → BaSO₄ + 2NaCl

Rotting of fruits and vegetables.

(c) (i), (ii) and (iv)

(d) Reversible

Correct answer is (b) white

It is a displacement reaction. Fe displaces Cu from CuSO₄.

Following are different steps of writing a chemical equation:

• Reactants’ symbols are written, followed by an arrow. A sign of addition (+) is written between formulae of two reactants.
• Products’ symbols are written on RHS of arrow.
• State of matter of reactants and products is shown by s (for solid), l(for liquid) and g (for gas) in brackets, after the formula.
• Special conditions, if any, is written above or below the arrow.
• Number of atoms of each element should be same on both sides of the arrow.

Characteristics of Chemical Equation
Chemical equation gives brief information about chemical reaction. 

They are as follows:

• Complete information about reactants and products, e.g. number of molecules, mass, etc.
• Physical states of substances.
• Necessary conditions for chemical equation, e.g. temperature, pressure, catalyst, etc.
• Equation also shows if reaction is exothermic or endothermic.
• Equation also shows reversibility of chemical reaction.

(a) X = Fe, Y = Fe₂O₃

Burning of coal is Oxidation  type of reaction.

Oxidation and reduction can be defined on following bases.
Association or decomposition of oxygen: 

When oxygen is added to a substance, the substance is said to
be oxidized. When oxygen is removed from a substance, the substance is said to be reduced. In other words, addition of oxygen is called oxidation and removal of oxygen is called reduction.

Example: 2Mg + O₂ → 2MgO

Association or decomposition of hydrogen: When  hydrogen is added to a substance, the substance is said to be reduced. When hydrogen is removed from a substance, the substance is said to be oxidized. In other words, addition of hydrogen is called reduction and removal of hydrogen is called oxidation.

Example: 2H₂S + O₂ → 2H₂O + 2S

Association or decomposition of electropositive elements: Removal of electropositive element from a substance is called oxidation. Addition of electropositive element to a substance is called reduction.

Example: 2Kl + Cl₂ → 2KCl + l₂

Association or decomposition of electronegative elements: Addition of electronegative element to a substance is called oxidation. Removal of electronegative element from a substance is called reduction.

Example: 2FeCl₃ + H₂ → 2FeCl₂ + 2HCl

Exchange of electrons: When an element loses electrons, it results in oxidation of that element. When an element gains electrons, its results in reduction of that element. 

Example: Na → Na⁺ + e^–, 2Cl^– → Cl₂ + 2e^–

(i) Oxidation of carbon and reduction of oxygen 

(ii) Oxidation of magnesium and reduction of chlorine 

(iii) Reduction of zinc oxide and oxidation of carbon 

(iv) Reduction of iron oxide and oxidation of carbon monoxide

It is a double displacement reaction.

The products obtained in the above reaction are as follows.

Na₂SO₄ + BaCl₂ → BaSO₄ + 2NaCl 

The reaction is double displacement.

The number of atoms on left hand side of the reaction (i.e., reactants) is equal to the number of atoms on the right hand side of the equation (i.e., product). Law of Conservation of Mass: Mass of atoms in chemical reaction can neither be created nor be destroyed, it remains the same.

The following observations in an activity may suggest that a chemical reaction has taken place:

• Change in state
• Change in colour
• Evolution of a gas
• Change in temperature

(c) double displacement reaction

(i) Oiling of metals 

(ii) Applying paints 

(iii) Making an alloy

(i) Vegetable matter changing into compost is exothermic and decomposition reaction. 

(ii) Burning of natural gas is exothermic reaction. 

(iii) Adding water to quick lime to form slaked lime is combination reaction and exothermic in nature.

pH = 7 will be the pH of a solution obtained after reaction between a strong acid and a strong base.

The reactant A is zinc metal and the reactant B is hydrochloric acid. 

Zn + 2HCl → ZnCl₂ + H_2.

The black coating of copper oxide can be removed chemically by passing hydrogen gas over heated copper oxide. The black coating turns brown as oxygen is removed by hydrogen.

Isotopes of uranium are used for production of electrical energy.

Molecular mass = Density x Molar 

volume Molar volume of CO₂ = 2.24 x 10^-2 m³ 

Density of CO₂ = 1.977 kg m^-3

Molecular mass of CO₂ = 1.977 x 10³ gm^-3 x 2.24 x 10^-2 m³ 

= 1.977 × 10 × 2.24 

= 44 g

(c) erythromycin

PABA is needed by many bacteria to produce folic acid.

(c) penicillin

(a) streptomycin

i) Penicillin, Tetracyline

ii) Both antiseptics and disinfectants are chemicals which either kill or prevent the growth of microorganisms.

iii) Antiseptics can be applied to living tissues such as wounds, cuts, ulcers, and diseased skin surfaces. But disinfectants are applied to inanimate objects such as floors, drainage systems, instruments, etc. They are harmful to live tissues.

Low level of nor adrenaline is responsible for the feeling of depression in human beings.

Iproniazid is a drug, used to counteract the effect of depression.

Carbohydrates are generally optically active because have one or more chiral carbon atoms in their molecules.

F.G. present in glucose = -CHO and -OH

F.G. present in fructose = C = O and -OH

Continuous spectrum of emission: When light is dispersed from a source spectrum of continuously distributed colours is obtained on a dark background is called a continuous spectrum of emission.

The correct answer is (b) Q₁ > Q₂, t₁ < t₂.

1. A set of genes will be switched on when a substrate is to be metabolized. 

2. This phenomenon is called induction and small molecule responsible for this, is known as inducer. 

3. It is positive control of gene regulation.

4. For example, lactose acts as an inducer in Lac operon.

2-Methoxypentane

The balanced reaction of combustion of carbon in dioxygens is:

C(s) + O₂(g) → CO₂ (g) 

1mole  1mole(32g)  1mole(44g)

(i) In dioxygen, combustion is complete. Therefore 1 mole of carbon dioxide produced by burning 1 mole of carbon. 

(ii) Here, oxgen acts as a limiting reagent as only 16 g of dioxygen is available. Hence, it will react with 0.5 mole of carbon to give 22 g of carbon dioxide. 

(iii) Here again oxgen acts as a limiting reagent as only 16 g of dioxygen is available. It is a limiting reactant. Thus, 16 g of dioxygen can combine with only 0.5 mole of carbon to give 22 g of carbon dioxide.

C + O₂ → CO₂

1 mole 32 g   44g

32 g oxygen produces 44 g CO₂

16 g oxygen will produce {44 x 16}/{32} g CO₂ = 22 g CO₂

(i) 1-Methoxy-2-methylbutane

(ii) hex-1-en-3-ol

The doctor showed great presence of mind on seeing the snake. He neither jumped nor cried out. He sat on the chair holding his breath. His body was still but his mind remained very active.

Correct answer is (d) work

False

The anode in electrolyte is positive.

Current can produce magnetic field is True.

1. higher, lower 

2. Conventional 

3. a pump 

4. 50 

5. electromechanical

Birds don’t get shocked when they sit on electrical wires because they are not good conductors of electricity. Electricity flowing through a single power line at 35,000 volts will continue along the path of least resistance and bypass birds, because there is no difference in electrical potential.

The electro-chemical process inside a battery provides electrons at the negative terminal and draws electrons from the positive terminal to maintain the current being drawn. By providing energy to the electrons, the cell is capable of maintaining an electric potential difference across the two ends of the external circuit.

‘हिन्दुस्तान हमारा है’ स्वरधारा हमारे देश में रहनेवाले कोटि-कोटि लोगों की है। जब से पृथ्वी और आकाश का उद्भव हुआ है और जब से आकाश में तारे छिटके और सूर्य-चांद बने हैं, तभी से हमारे देश का अस्तित्व है। इस तरह यह स्वरधारा अनादि-आदि काल से हैं।

कवि बालकृष्ण शर्मा ‘नवीन’ भारत के लिए कहते हैं कि हमारा देश भारतवर्ष बहुत प्राचीन देश है। यह अनादि-आदि काल से हमारा जन्म-स्थान है। इस बात का देश के बयालीस करोड निवासियों को गर्व है। उनकी गर्जना सुनकर दुश्मनों के हदय सिहर उठते हैं। उनका सामना कोई नहीं कर सकता। भारतवर्ष एक महान देश है।

भारत का स्वतंत्रता आंदोलन यहाँ अपनी सत्ता जमाए बैठे अंग्रेजों के खिलाफ था। कवि उन्हीं को भारत का प्रतिपक्षी मानते हैं।