An element has an atomic number of $56$. To which of the following does it belong?

Beryllium resembles much with

When $CO_2$ gas is passed through lime water,it turns milky. On passing excess $CO_2$ gas,the milkiness disappears because:

Which of the following statements is incorrect?

$A$ compound $X$ on heating gives a colourless gas. The residue is dissolved in water to obtain $Y$. Excess $CO_2$ is bubbled through the aqueous solution of $Y$ and $Z$ is formed. $Z$ on gentle heating gives back $X$. The compound $X$ is:

Which of the following statements is not correct?