The number of acidic hydrogen atoms in $but-1-yne$ is ........

Which of the following is not a conjugate acid-base pair?

Which one of the following elements shows the maximum number of different oxidation states in its compounds?

Which organisms obtain nutrition through both photosynthesis and absorption?

The electron affinity values of elements $A, B, C$ and $D$ are respectively $-135, -60, -200$ and $-348 \ kJ \ mol^{-1}$. The outer electronic configuration of element $B$ is

$A$ uniform magnetic field $B$ that is perpendicular to the plane of the page passes through the loops,as shown. The field is confined to a region of radius $a$,where $a < b$,and is changing at a constant rate. The induced emf in the wire loop of radius $b$ is $\varepsilon$. What is the induced emf in the wire loop of radius $2b$?