21.

 Name the gas in each of the following:

The gas produced when excess ammonia reacts with chlorine.

Some word/words are missing in the following statement.  You are required to rewrite the statement in the correct form using the appropriate word/words:

Magnesium nitride reacts with water to liberate ammonia

Name the gas in each of the following:

The gas produced when copper reacts with concentrated nitric acid.

Some word/words are missing in the following statements. You are required to rewrite the statement in the correct form using the appropriate word/words:

Magnesium reacts with nitric acid to liberate hydrogen gas.

Choose the correct answer from the option given below:

An element in period -3 whose electron affinity is zero:

• Neon

• Sulphur

• Sodium

• Sodium

An alkaline earth metal:

• Potassium

• Calcium

• Lead

• Lead

Choose the correct answer from the options given below:

The Vapour density of carbon dioxide [C=12,O=16]

• 32

• 16

• 44

• 44

Choose the correct answer from the options given below:

Identify the weak electrolyte from the following:

• Sodium chloride solution

• Dilute Hydrochloric acid

• Dilute sulphuric acid

• Dilute sulphuric acid

Choose the correct answer from the options given below:

Which of the following metallic oxides cannot be reduced by normal reducing agents

• Magnesium oxide

• Copper (II) oxide

• Zinc oxide

• Zinc oxide

Give reasons  for the following:

The ionisation potential of the element increases across a period.