Which of the following is the correct statement for red lead?

Identify the incorrect statement.

Give the chemical reaction for preparing pure $CO$.

Polyphosphates are used as water softening agents because they .......

Reaction of $NaCl$ with conc. $H_2SO_4$ liberates a gas,$X$ that turns moist blue litmus paper red. When gas $X$ is passed into a test tube containing egg shell powder suspended in water,another gas,$Y$ is generated which when passed through lime water makes it milky. The gases $X$ and $Y$,respectively,are

$CO_2$ and $N_2$ do not support combustion. However,$CO_2$ is preferred over $N_2$ for extinguishing fires because $CO_2$ .......