Blue litmus solution is added to two test tubes A and B containing dilute HCl and NaOH solution respectively. In which test tube a colour change will be observed? State the colour change and give its reason.
OR
What is observed when 2 mL of dilute hydrochloric acid is added to 1 g of sodium carbonate taken in a clean and dry test tube? Write chemical equation for the reaction involved.
Blue litmus turns red when it comes in contact with an acid. So Test tube A containing HCl will change the colour. It will turn red from blue.

OR
HCl is an acid and sodium carbonate is a base. When an acid and a base react they form salt and water. This is called a neutralisation reaction.
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When 2 ml of dil HCl is added to 1 g of sodium carbonate a brisk effervescence is observed.
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