Helium is preferred to hydrogen for filling balloons because it is

1. lighter than air
2. almost as light as hydrogen
3. non-combustible
4. inflammable

Upon reacting with water, an active metal produces

1. oxygen
2. nitric acid
3. a base
4. none of these.

Which of the following statements about hydrogen is incorrect ?

1. It is an inflammable gas
2. It is the lightest gas.
3. It is not easily liquefied.
4. It is a strong oxidizing agent.

For the reaction PbO + H₂ ⟶ Pb + H₂O, which of the following statements is wrong?

1. H₂ is the reducing agent.
2. PbO is the oxidizing agent.
3. PbO is oxidized to Pb
4. H₂ is oxidized to H₂O.