$A$ certain metal is used in the preparation of antacids. This metal accidentally catches fire and cannot be extinguished using $CO_2$. Which metal is this?

The ratio of minimum wavelengths of Lyman and Balmer series will be

$A$ molecule $(X)$ has $(i)$ four sigma bonds formed by the overlap of $sp^2$ and $s$ orbitals,$(ii)$ one sigma bond formed by $sp^2$ and $sp^2$ orbitals,and $(iii)$ one $\pi$ bond formed by $p_z$ and $p_z$ orbitals. Which of the following is $X$?

In which of the following reactions is the product an ether?

Three unequal resistors in parallel are equivalent to a resistance $1 \, \Omega$. If two of them are in the ratio $1 : 2$ and if no resistance value is fractional,the largest of the three resistances in $ohms$ is

Which layer of the alimentary canal is responsible for peristalsis?