Consider the following statements:

$1.$ The energy of the electrons in the orbit is quantized.
$2.$ Electrons revolve only in those orbits for which angular momentum is not an integral multiple$\frac{h}{2\mathrm{\pi }}$.
$3.$ The electrons don't revolve in different orbits around the nucleus.

$4.$ The electrons emit energy during revolution due to the presence of coulombic forces of attraction.

Which of the statements given above is/are correct about Bohr's model of an atom?

Consider the following statements:

1. Bryophytes are amphibians of the plant kingdom.

2. They are found in swamps, the areas where water and land meet.

Which of the statements given above is/are correct?

Which of the following statements about the commonly used automobile battery are true?

$1$. It is usually a lead-acid battery.
$2$. It has $6$ cells with a potential of $2$V each.
$3$. Its cells work as galvanic cells while discharging power.
$4$. Its cells work as electrolytic cells while recharging.

Select the correct answer using the codes given below.

Consider the following statements:

1.The force by which water moves upwards into the treachery element of xylem in the root region is root pressure.

2. Root pressure is measured by a manometer.

3. Water will be absorbed by root hairs when the external medium is hypotonic.

4. Cohesion Tension theory for the ascent of sap was given by Dixon and Jolly.

Which of the statements given above are correct?

Consider the following statements:

Which of the statements given above are correct?

Consider the following statements:

$1$. Glucagon is secreted by $\alpha$-cells of islets.
$2$. Insulin is secreted by $\beta$-cells.
$3$. Insulin deficiency causes diabetes mellitus.

Which of the statements given above are correct about pancreatic hormones?