1
MHT CET (PCB) 2025 9th April Evening Shift
MCQ (Single Correct Answer)
+1
-0

In the Bohr model of hydrogen atom, out of the following quantities, the principal quantum number is proportional to ( $\mathrm{R}, \mathrm{V}$ and E represent radius of the orbit, speed of electron and total energy of the electron respectively)

A

$\frac{\mathrm{V}}{\mathrm{R}}$

B

VR

C

$\frac{E}{V}$

D

$\frac{E}{R}$

2
MHT CET (PCB) 2025 9th April Evening Shift
MCQ (Single Correct Answer)
+1
-0

An open organ pipe and a closed organ pipe have the frequency of their second overtone identical. The ratio of length of closed pipe to that of open pipe is (Neglect end correction)

A

$2: 3$

B

$5: 6$

C

$3: 4$

D

$6: 7$

3
MHT CET (PCB) 2025 9th April Evening Shift
MCQ (Single Correct Answer)
+1
-0

An object is released from a distance ' $r$ ' from the centre of the earth. The velocity of the object at the time of striking the earth will be ( $R=$ radius of earth, $r>R, g=$ acceleration due to gravity)

A

$[2 \mathrm{gR}(\mathrm{r}-\mathrm{R}) / \mathrm{r}]^{\frac{1}{2}}$

B

$\left[g R(r-R) / r^2\right]^{\frac{1}{2}}$

C

$\quad\left[2 \mathrm{gR}(\mathrm{r}-\mathrm{R}) / \mathrm{r}^2\right]^{\frac{1}{2}}$

D

$\left[g R^2(r-R) / r^2\right]^{\frac{1}{2}}$

4
MHT CET (PCB) 2025 9th April Evening Shift
MCQ (Single Correct Answer)
+1
-0

According to Bohr's first postulate the kinetic energy $\frac{1}{2} m v^2$ of the electron in C.G.S. system is ( $\mathrm{m}=$ mass of electron, v is its velocity, r is the radius of the stationary orbit around the nucleus with charge Ze )

A

$\frac{\mathrm{Ze}}{\mathrm{r}^2}$

B

$\frac{\mathrm{Ze}^2}{\mathrm{r}}$

C

$\frac{\mathrm{Ze}^2}{2 \mathrm{r}}$

D

$\frac{\mathrm{Ze}^2}{2 \mathrm{r}^2}$