Atmospheric Pollution — CHEMISTRY STD 9 — Question

Hydrogen may be prepared in the laboratory by the action of a metal on an acid.
Which of the metals copper, zinc, magnesium or sodium would be the most suitable?

State the original colour of the following substance and colour of residue obtained after heating.
Ammonium dichromate

What is a pollutant?

Name: Gas with rotten egg smell.

Write the balanced equation and give your observation when the following metal reacts:
Sodium with cold water

Name the following:
Two atoms having the same number of protons and electrons but different number of neutrons.

Identify the gases from the observations:
A colourless and odourless gas, which is neutral towards litmus. It explodes with a ‘pop” sound when a burning wooden splint is held near it.

In the formation of magnesium chloride (by direct combination between magnesium and chlorine), name the substance that is oxidized and the substance that is reduced.

Explain why:
If distilled water is kept in a sealed bottle for a long time, it leaves etchings on the surface of the glass.

Name a metal which reacts vigorously with dilute HCI.