What is the formula mass of anhydrous sodium carbonate? (Given that the atomic masses of sodium, carbon and oxygen are 23 u, 12u and 16 u respectively).

• 286 u

• 106 u

• 83 u

• 53 u

Which one of the following is called 'syngas'?

• C(s) + H₂O(g)

• CO(g) + H₂O(g)

• CO(g) + H₂(g)

• NO₂(g) + H₂(g)

A stainless steel chamber contains Ar gas at a temperature T and pressure P. The total· number of Ar atoms in the chamber is n. Now Ar gas in the chamber is replaced by CO, gas and the total number of CO, molecules in the chamber is n/2 at the same temperature T. The pressure in the chamber now is P'. Which one of the following relations holds true? (Both the gases behave as ideal gases)

• P' = P

• P' = 2P

• P' = $\frac{\mathrm{P}}{2}$

• P' = $\frac{\mathrm{P}}{4}$

Permanent hardness of water cannot be removed by which one of the following methods?

• Treatment with washing soda

• Calgon's method

• Boiling

• Ion exchange method

Which one of the following reactions will give NO (nitric oxide) gas as one of the products?

• 3Cu + 8HNO₃ (dilute) →

• Cu + 4HNO₃ (conc.) →

• 4Zn + 10HNO₃ (dilute) →

• Zn + 4HNO₃ (conc.) →

Which one of the following is a tribasic acid?

• Hydrochloric acid

• Nitric acid

• Sulphuric acid

• Phosphoric acid

Which one of the following statements is not correct?

• All carbons in diamond are linked by carbon-carbon single bond.

• Graphite is layered structure in which layers are held together by weak van der Waals forces.

• Graphite layers are formed by hexagonal rings of carbon atoms.

• Graphite layers are held together by carbon-carbon single bond.

28.

Which one ofthe following is called dry ice?

• Solid carbon dioxide

• Liquid carbon dioxide

• Liquid nitrogen

• Liquid ammonia

Which one of the following is not an agent of metamorphism?

• Heat

• Compression

• Decomposition

• Solution

The solution of which one of the following will have pH less than 7?

• NaOH

• KCl

• FeCl₃

• NaCl