Question

Which of the following elements would form oxides which would indicate pH values less than seven, using moist pH paper ?
Magnesium, Carbon, Sulphur, Hydrogen , Copper

Lakhmir Singh Chemistry Class 10

Answer 1

Answer:

Using moist pH paper Sulphur and Carbon will show pH value less than 7.  When a proton is being donated by an ion or a molecule, it is called acid.

Carbon on reacting with oxide becomes carbon dioxide, which gives carbonic acid on dissolving in water. Sulphur on reacting with oxide becomes  Sulphur dioxide, which gives acid rain on dissolving in water.

So, both Carbon dioxide and Sulphur dioxide are in gaseous state, and gives acidic product on reaction with water.  

Answer 2

Answer:-

Carbon and Sulphur being non-metals form acidic oxides. So, oxides of Carbon and Sulphur will have pH value less than 7.