Question

2g of NaCl is taken in a dry test tube fitted with a delivery tube. On adding conc. Sulphuric acid to the test, a gas with white fumes is evolved. When a dry blue litmus paper is brought in contact with gas, there is no change in the colour of the litmus.

Answer 1

what is the question in the lines that u have typed??

Answer 2

Answer:

TO observe gas is acidic we need to brought in contact wet blue litmus paper with gas, it's  change into red colour of the blue litmus paper.  

Explanation:

when NaCL (SODIUM CHLORIDE) is taken in dry test tube is fitted with a delivery tube and adding concertrated H2SO4 (SULPHURIC ACID) to the test tube. it reaction takes place turn into HCL (hydrochloric acid). HCL GAS COMES OUT WITH WHITE FUME IS EVOLVED.

In gas there is no H+ and H+3O ions is not there.

so, When a dry blue litmus paper is brought in contact with gas, there is no change in the colour of the litmus.

when we wanted observe gas is acidic we need to brought in contact wet blue litmus paper with gas, it's  change into red colour of the blue litmus paper.  

wet litmus paper is having  H+ and H+30 ions. it combines with gas.

then it turns blue into red litmus paper.

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