Question

When a white powdered substance 'X' is added to dilute HCl in a test tube, a brisk effervescence is observed with the liberation of a gas. A burning candle, brought near the mouth of test tube, is extinguished. Substance 'X' can be

Answer 1

Answer:

Zinc, Magnesium, Iron or Aluninium

Explanation:

When these metals react with dilute HCL the products are a salt plus hydrogen gas which puts out the burning candle

Answer 2

The substance X is Calcium Carbonate (CaCO3).

• When a burning candle is brought near the mouth of the test tube, it is extinguished therefore the gas evolved must be CO2.
• The white powdered substance must be CaCO3, which is an insoluble substance, which when reacts with dilute HCL produces a colourless and odourless gas CO2 which turns the lime water milky due to precipitation.