Calcium phosphate is present in tooth enamel. Its nature is

How is bleaching powder prepared? Why does bleaching powder $(i)$ not dissolve completely in water?

$R$. $K$. Patel,a chemistry teacher,explained the properties of inorganic acids in Std. $10$. He intentionally stated one of the properties incorrectly. Identify which one was wrong.

What is the effect of an acid on litmus paper?

How would you distinguish between baking powder and washing soda by heating?

$(a)$ Tooth enamel is one of the hardest substances in our body. Explain the changes in $pH$ of the mouth that indicate tooth decay. How does toothpaste help in preventing it?
$(b)$ What is the nature of the salt if the $pH$ of its solution is greater than $7$? Name the acid and base that would be used to prepare the following salts:
$(i)$ Potassium sulphate.
$(ii)$ Ammonium chloride.