Physics Past Questions and Answers

Question 4731:

Which of the following conditions will make water boil at a temperature of 100 degrees Celsius when the atmospheric pressure is $750\mathrm{mmHg}$ ?

A. Increase the external pressure
B. Reduce the external pressure
C. Heat more rapidly at the same pressure
D. Reduce the external pressure by a quarter

Question 4732:

A solid weighs $4.8\mathrm{g}$ in air, $2.8\mathrm{g}$ in water and $3.2\mathrm{g}$ in kerosene. The ratio of density of the solid to that of the kerosene is ____________

A. 12
B. 3
C. 2
D. $3/2$
E. $5/4$

Question 4733:

The extension in spring when $5\mathrm{g}$ weight was hung from it was $0,56\mathrm{cm}$. if Hooke's law is obeyed, what is the extension caused by a load of $20\mathrm{g}$ weight?

A. $1.12\mathrm{cm}$
B. $2.14\mathrm{cm}$
C. $2.52\mathrm{cm}$
D. $2.80\mathrm{cm}$
E. $2.24\mathrm{cm}$

Question 4734:

The ice and steam points of a mercury-in-glass thermometer of centigrade scale and of uniform bore correspond respectively to $3\mathrm{cm}$ and 19 em lengths of the mercury thread. When the thread is $12\mathrm{cm}$, the temperature is ____________

A. ${32}^{\circ }\mathrm{C}$
B. ${48}^{\circ }\mathrm{C}$
C. ${56}^{\circ }\mathrm{C}$
D. ${65}^{\circ }\mathrm{C}$
E. ${75}^{\circ }\mathrm{C}$

Question 4735:

An electric cell has an internal resistance of 2 ohms, a current of $0.5\mathrm{A}$ is found to flow when $a$ resistor of 5 ohms resistance is connected across it. What is the electromotive force of the cell?

A. 5 volts
B. $3.5$ volts
C. $2.5$ volts
D. 1 volt
E. 10 volts