Choose the incorrect pair for the characters given by Mendel.
Character $\quad$ Dominant $\quad$ Recessive

The enzyme ptyalin used for the digestion of food is present in:

$A$ student has to answer $10$ out of $13$ questions in an examination,choosing at least $5$ questions from the first $6$ questions. The number of choices available to the student is:

Assertion $(A)$: The $pH$ of a buffer solution containing equal moles of acetic acid and sodium acetate is $4.8$ ($pK_a$ of acetic acid is $4.8$).
Reason $(R)$: The ionic product of water at $25^{\circ} C$ is $10^{-14} \ mol^2 \cdot L^{-2}$. The correct answer is

Which of the following statements about the Bohr model of the hydrogen atom is false?

The period of $\sin ^4 x + \cos ^4 x$ is