Which of the following pairs represents isoelectronic ions?

• Na⁺, K⁺

• K⁺, Mg²⁺

• Mg²⁺, Ca²⁺

• Ca²⁺, S^2-

Dihydrogen can be prepared on a commercial scale by the action ofsteam on hydrocarbons, when a mixture of CO and H₂ gas is formed. It is known as

• water gas

• producer gas

• industrial gas

• fuel gas

Which of the following statements about hydrogen is/are correct?

1. Hydrogen has three isotopes of which protium is the most common
2. Hydrogen ion (H⁺) exists freely in solution.
3. Dihydrogen, H₂, acts as a reducingagent.

Select the correct answer using the code given below

• 1, 2 and 3

• 1 only

• 1 and 3 only

• 3 only

Which of the following statements is correct?

• Fullerenes have only six-membered carbon rings

• Fullerenes are cage-like molecules

• Diamond is thermodynamically the most stable allotrope of carbon

• Graphite is slippery and hard, and is therefore used as a dry lubricant in machines

Which of the following acids is a mineral acid?

• Citric acid

• Hydrochloric acid

• Ascorbic acid

• Tartaric acid

Which of the following is correct regarding the reaction of fluorine with water?

2F₂(g) + 2H₂O(l) → 4H⁺(aq) + 4F^-(aq) + O₂(g)

• Fluorine is oxidized to F^-

• Water is oxidized to O₂

• Water is reduced to H⁺

• Oxidation state of fluorine does not change

Which of the following is/are amphoteric?

• AI(OH)₃(s) and Fe(OH)₃(s)

• AI(OH)₃(s) and HCO^-₃(aq)

• Ba(OH)₂(s) and NaOH(aq)

• AI(OH)₃(s) only

148.

The most of the mass of the atom can be found in

• electrons

• charges

• nucleus

• electron cloud

The pressure of an ideal gas undergoing isothermal change is increased by 10%. The volume of the gas must decrease by about

• 0.1 %

• 9%

• 10%

• 0.9%

The mass number of an atom is determined by

• adding the number of neutrons and number of electrons

• adding the number of protons and number of electrons

• the number of protons only

• adding the number of neutrons and number of protons