Note the following balanced chemical equation:

2CO +O₂ $\rightleftharpoons$ 2CO₂

_{Which one of the following statements is significant in relation to the above chemical equation?}

• One can add to a vessel only 2 mol of CO for each mol of O₂ added

• No matter how much ofthese two reagents are added to a vessel, 1 mol of O₂ is consumed

• When they react, CO reacts with O₂ in a 2:1 mol ratio

• When 2 mol of CO and 1 mol of O₂ are placed in a vessel, they will react to give 1 mol of CO₂

A fertilizer contains 20% nitrogen by mass. To provide a fruit tree with .an equivalent of I kg of nitrogen, the quantity of fertilizer required is

• 20 kg

• 0.20 kg

• 0.05 kg

• 5 kg

A sample of carbon dioxide that undergoes a transformation from solid to liquid and then to gas would undergo

• a change in mass

• a change in density

• a change in composition

• no change in physical properties

Which of the following element combinations will form ionic compounds?

1. Ca (Z= 20) and Ti (Z = 22)
2. Si (Z= 14) and Br (Z= 35)
3. Mg (Z = 12) and Cl (Z = 17)

Select the correct answer using the code given below.

• 2 only

• 3 only

• 2 and 3 only

• 1, 2 and 3

A compound X₂O₃ contains 31.58% oxygen by weight. The atomic mass of X is

• 34.66 g mo1^-1

• 45.01 g mo1^-1

• 52.00 g mo1^-1

• 104.00 g mo1^-1

Which one among the following contains the most neutrons?

• ${}_{26}{}^{59}\mathrm{Fe}$

• ${}_{29}{}^{61}\mathrm{Cu}$

• ${}_{30}{}^{61}\mathrm{Zn}$

• ${}_{30}{}^{61}\mathrm{Zn}^{2+}$

157.

The very high heat of vaporization of water is mainly a result of

• van der Waals forces

• covalent bonds

• interionic attraction

• hydrogen bonding

What is the oxidizing agent in the following equation? HAsO₂(aq) + Sn²⁺(aq) + H⁺(aq) → As(s) + Sn⁴⁺(aq) + H₂O(I)

• HAsO₂ (aq)

• Sn²⁺(aq)

• H⁺(aq)

• Sn⁴⁺(aq)

Which one of the following substances is most likely to be used as soap?

• CH₃(CH₂)₁₂COOCH₃

• CH₃(CH₃)₅O(CH₂)₅CH₃

• CH₃(CH₂)₁₂COONa

• CH₃(CH₂)₁₂CHCl₂

A sample of gas is to be identified by means of its behaviour in the presence of a glowing splint. Which of the following gases will neither itself burn nor cause the splint to burn?

• Oxygen

• Nitrogen

• Hydrogen

• Methane