181.

Biogas consists of mainly

• Methane

• Ethane

• Butane

• Carbon dioxide

A gas is evolved when a piece of zinc metal is placed in dilute sulphuric acid (H₂SO₄). What is the gas?

• Hydrogen

• Oxygen

• Water vapour

• Sulphur dioxide

Turmeric (Haldi) rapidly becomes colourless on addition of

• Baking soda

• Vinegar

• Lemon juice

• Alcohol

Metalloids are

• alloys of alkali metals with other metals

• colloids of metals

• elements having some properties of both metals and non-metals

• metals heavier than lead

Two reactants in a flask produce bubbles of gas; it turns lime water into milky. The reactants in the flask are

• Zinc and hydrochloric acid

• Magnesium carbonate and hydrochloric acid

• Magnesium nitrate and hydrochloric acid

• Magnesium sulphate and hydrochloric acid

Which one among the foliowing transitions is associated with the largest change in energy in hydrogen atom?

• n= 5 to n= 3

• n= 2 to n= 1

• n= 3 to n= 2

• n= 4 to n= 2

Match List-I with List-II

List I (Compound)

1. Cellulose nitrate
2. Potassium sulphate
3. Potassium salt of fatty acids
4. Calcium oxide

List II (Use)

1. Soft soap
2. Gun powder
3. Fertilizer
4. Glass

• (a) - 2, (b) - 3, (c) - 1, (d) - 4

• (a) - 2, (b) - 1, (c) - 3, (d) - 4

• (a) - 4,(b) - 1, (c) - 3, (d) - 2

• (a) - 4, (b) - 3, (c) - 1, (d) - 2

Which one among the following equations is correctly balanced?

• NaOH + AI + H₂O → 2H₂ + NaAIO₂

• 2NaOH + 2AI + 2H₂O → 3H₂ + 2NaAIO₂

• 2NaOH + 2AI + 3H₂O → 4H₂ + 2NaAIO₂

• 2NaOH + 2AI + H₂O → H₂ + 2NaAIO₂

Three elements Na, S and O combine to form a compound Na₂SO₃. What is the valency of S in this compound?

• 2+

• 4+

• 6+

• 8+

Which one among the following is the equivalent weight of sulphuric acid? (Atomic weight: H =1,S = 32, O = 16)

• 98

• 60

• 100

• 49