Two balls of same mass and carrying equal charge are hung by threads of length $l$ from a fixed support. At electrostatic equilibrium, assuming that angles made by each thread is small, the separation, $x$ between the balls is proportional to:

(a.) $l$

(b.) $l^2$

(c.) $l^{2/3}$

(d.) $l^{1/3}$

Based on the passage, which of the following best captures the meaning of HIF, or hypoxia-inducible factor?

A. It is a protein that increases inside the cell when the oxygen levels fall, helping the cell survive.
B. It inhibits oxygen carrying process in the body as the oxygen level increases inside the cell.
C. It enables cells to adapt quickly to the changing environment and helps in its survival.
D. It regulates the amount of oxygen available to the cell and the body during exercise.

Assertion (A): Beryllium carbonate is kept in the atmosphere of carbon dioxide. Reason (R): Beryllium carbonate is unstable and decomposes to give beryllium oxide and carbon dioxide.

(A) Both A and R are correct and A is the correct explanation of R.

(B) Both A and R are correct but A is not the correct explanation of R.

(C) Both A and R are not correct.

(D) A is not correct but R is correct.

In the following questions a statement of Assertion (A) followed by a statement of Reason (R) is given. Choose the correct option out of the choices given below each question.

Assertion (A): The carbonate of lithium decomposes easily on heating to form lithium oxide and CO₂⋅

Reason (R): Lithium being very small in size polarises large carbonate ion leading to the formation of more stable Li₂O and CO₂.

(A) Both A and R are correct and R is the correct explanation of A.

(B) Both A and R are correct but R is not the correct explanation of A.

(C) Both A and R are not correct.

(D) A is not correct but R is correct.

Match the elements given in Column I with the colour they impart to the flame given in Column II.

Match the compounds given in Column I with their uses mentioned in Column II.