Chemistry
Helium is preferred to hydrogen for filling balloons because it is
- lighter than air
- almost as light as hydrogen
- non-combustible
- inflammable
Related Questions
Under what conditions can hydrogen be made to combine with
(a) nitrogen
(b) chlorine
(c) sulphur
(d) oxygen
Name the products in each case and write the equation for each reaction.
When hydrogen is passed over a black solid compound A, the products are 'a colourless liquid' and 'a reddish-brown metal B.'
Substance B is divided into two parts, each placed in separate test tubes.
Dilute HCl is added to one part of substance B and dilute HNO3 to the other.
(a) Name the substances A and B.
(b) Give two tests for the colourless liquid formed in the experiment.
(c) What happens to substance A when it reacts with hydrogen ? Give reasons for your answer.
(d) Write an equation for the reaction between hydrogen and substance A.
(e) Is there any reaction between substance B and dilute hydrochloric acid ? Give reasons for your answer.
Upon reacting with water, an active metal produces
- oxygen
- nitric acid
- a base
- none of these.
A metal oxide that is reduced by hydrogen is:
- Al2O3
- CuO
- CaO
- Na2O