Explore topic-wise InterviewSolutions in Current Affairs.

1. The focal length of a concave mirror independent of the medium and A convex lens depends on medium when they are placed in water. The focal length of the mirror – Does not change. 

2. The focal length of the convex lens – Changes (means increases 4 times).

Electrolysis is the process of dissociation of water molecules into H⁺ and OH^– ions. When electric current Is passed through it in a conducting state. Because water does not have much higher concentration of ions. Dilute sulphuric acid is added to increase the concentration of ions in the water.

Both, convex lens and concave mirror, converge parallel rays of light coming from infinity (parallel to the principal axis) at the focus.

(a) Oxygen Gas is produced at positive carbon electrode. 

(b) Hydrogen gas is produced as negative carbon electrode.

(a) The spot color is Greenish blue. 

(b) The coloured spot is formed around the positive electrode. 

(c) This is known as Chemical effect.

(C) mosquitoes

Rainwater contains dissolved salts. This makes it a conducting solution. There are no dissolved salts present in the distilled water. Hence, rainwater can allow electricity to pass through it while distilled water cannot

(D) II, III, IV 

(II) H₃O⁺ (III) NH₃ (IV) CH₃^-

C. electrolysis 

Electrolysis is the decomposition produced by passing current through a conducting liquid. The solution is dissociated into ions.

The three types of substances in which an electric current can produce a chemical effect. 

1. Water 

2. Copper sulphate 

3. Vinegar.

(d) chemical, heating, and magnetic effects.

D. electrolytic cell 

An electrolytic cell is an arrangement having two carbon rods kept in a conducting liquid in a vessel. This is the process setup for the electrolysis of electrolytes.

D. LED

LED Light emitting diode is used to detect very small current flowing in an electric circuit.

(d) vegetable oil

When electric current is passed through acidified water, it dissociates water into H⁺ and OH^– ions. This process is called chemical effect.

 Use of convex mirror: As rear-view mirror in vehicles

Use of concave mirror: As shaving mirrors

Use of convex lens: For making simple camera

Use of concave lens: As eye-lens in Galilean telescope

Correct option is (d) 3.125 x 10^-2

Correct option is (b) 818.75 x 10^-2

Correct option: (B) 3.125 x 10^-2 

1 mole of Mg₃(PO₄)₂ gives 8 moles of O₂

x moles will give 0.25 moles of O₂

x = \(\cfrac{0.25}{8}\) = 3.125 x 10^-2 moles.

Rain water can collect salts from the atmosphere has some dissolved salts whereas the distilled water does not. Thus, the rainwater showed the deflection because it conducts electricity.

The water which we get from sources such as taps, hand pumps, well and ponds is not pure. It has dissolved salts in it. These dissolved salts help in conduction of electricity making it a good conductor of electricity.

No. Pure water does not conduct electricity. Pure water does not contain any ions which make it conducting. But it can conduct electricity when a pinch of common salt is added to it, as salt solution is conducting in nature.

Lemon juice is a good conductor of electricity. Lemon is a citrus fruit containing citric acid. Acids give H+ ions when dissolved in water, these free cations and anions make lemon juice a good conductor.

When electric current passes through a conducting liquid, it gets decomposed into ions. The conducting solution has free ions available which conduct electricity.

Correct option is (d) 0.10

Vinegar is a poor conductor of electricity because it does not have any free ions to carry electric charge and conduct electricity.

(a) False. Rainwater is a conductor of electricity because it has dissolved ions that conduct electricity. 

(b) False. A piece of fresh potato conduct electricity at all because it does not have ions to conduct electricity.

B. Sugar solution 

Sugar solution does not contain any ions. Thus, it does not conduct electricity.

Liquids do conduct electricity, when they have free ions available like in case of Acids, Bases and Salts being dissolved in water.

A pungent smelling reddish brown coloured gas (NO₂) is produced and the solution turns greenish blue. 

Cu + 4HNO₃ (cone.) → Cu (NO₃ )₂ + 2H₂O + 2NO₂

Vinegar is mostly acetic acid dissolved in water. It contains ions and conducts
electricity.

Sea water is a better conductor because it contains sodium and chloride ions in large amounts. These ions make the solution conducting and thus, sea water is considered better conductor than the tap water which does not contain ions in large amounts.

No, all liquids do not conduct electricity. The liquids require free ions in them to conduct electricity.

Distilled water does not conduct electricity because it does not contain any ions which make it conducting. But it can conduct electricity when a pinch of common salt is added to it, as salt solution is conducting in nature.

Distilled water is pure form of water. This do not contain ions. No electricity flows in distilled water. But rain water is impure and contains ionic groups.

Ex: Acids. Hence rain water is conductor of electricity.

(i) Tap water contains ions which conduct electricity, distilled water does not contain ions. 

(ii) Dry HCl does not form ions but HCl gives H⁺ and Cl^– . 

(iii) Baking soda does not allow milk to change to lactic acid which makes milk sour. 

(iv) Adding water to acid is highly exothermic. Therefore water is added to acid very slowly with cooling. 

(v) Ammonia dissolves in water and forms H^– Therefore, it is basic in nature. 

Aqueous solution of acids have H⁺ ions which carry electric current through the solution.

1. a. Displacement of mercury from mercuric chloride.

2. b. Zinc

3. a. Sodium

4. c. Galvanisation

5. a. METAL

(D) all of the above

HCI will give rise to more H⁺ ions and CH₃COOH produces less H⁺ ions on dissociation. The colour of pH paper depends on the concentration of H⁺ ion. Colour becomes red for high H⁺ concentration

Half the inter-nuclear distance between two similar atoms of any element which are covalently bonded to each other by a single covalent bond is called covalent radius.

(i)  Atomic radius: The distance from the centre the nucleus to the outermost shell of an atom. 

(ii) Covalent radius: One half of the distance between the nuclei of two covalently bonded atoms.

(iii) Metallic radius: Half the inter nuclear distance separating the metal cores in the metallic crystal

Green colour will be obtained.

Metal oxides have relatively high melting points. Here both iron and calcium are metals, but iron oxide is insoluble in water.

(a) calcium.

Lithium forms covalent bond which is different from its group members because of its anomalous behaviour Li is small in size, large charge / radius ratio and has high electro negativity value. Also it has only 1s² 2s¹ orbital for bonding.

(i) A large amount of energy is required to break the strong inter-ionic attraction.

(ii) When ionic compounds is present in molten state, crystal structure deforms and they can easily conduct electricity with the mobile ions.

(iii) Due to the strong force of attraction between the positive and negative ions.

In ionic compounds, cations and anions are held together by strong electrostatic forces of attraction. Hence large amount of energy is required to overcome these forces.

Cation: Mg⁺⁺

Anion: O^--

Ionic compounds hive high melting point because cations and anions are held by strong electrostatic force of attraction,and considerable amount of  energy is required, to break the, strong inter ionic forces.