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UPSC Civil services Entrance exams General Studies test # General Science Laws of Motion Prepare / Learn

Q1. A nucleus is at rest in the laboratory frame of reference. If it disintegrates into two smaller nuclei

A. the products must move at an angle in opposite directions.

B. the products must move in opposite directions.

C. the products must move in same direction.

D. the products must move at an angle in same direction.

Answer : Option B
Explaination / Solution:

Let, M = mass of nucleus at rest . m1 and m2 are masses of two smaller nuclei. v1 and v2 are the velocities of respective masses

Now, According to the law of conservation of momentum,

Initial momentum before disintegration = final momentum after disintegration

$m_{1} v_{1} + m_{2} v_{2} = 0$

$v_{2} = - \frac{m_{2}}{m_{1}} \cdot v_{1}$

As masses $m_{1}$ and $m_{2}$ cannot be negative, $v_{1}$ and $v_{2}$ having opposite signs and so the two smaller nuclei move in opposite directions.

UPSC Civil services Entrance exams General Studies test # General Science Biotechnology and its Applications Prepare / Learn

Q2. DNA is denatured to produce single strand by

A. chelators

B. Acidic solution

C. Alkaline solution

D. oxidising agents

Answer : Option C
Explaination / Solution:

Deoxyribose nucleic acid is denatured to produce single stranded by using alkaline solution. DNA is acidic in nature, in alkaline solution the hydrogen bonds between the nitrogenous bases is broken to separate two strands.

UPSC Civil services Entrance exams General Studies test # General Science Reproductive Health Prepare / Learn

Q3. Human population growth is

A. Exponential

B. Stationary

C. Sigmoid

D. Lag

Answer : Option A
Explaination / Solution:

Human population growth is exponential growth which gets doubled every time. The newly produced individual also participates in population increase after attaining puberty.

UPSC Civil services Entrance exams General Studies test # General Science Current Electricity Prepare / Learn

Q4. orders of magnitude of random electron motion speed to drift speed are like

A. 106m/s,10−4m/s

B. 102m/s,102m/s

C. 104m/s,10−2m/s

D. 103m/s,10−1m/s

Answer : Option A
Explaination / Solution:

The random velocities of electrons is of the order 105 to 106 m/s, while the drift velocities are of the order 0.1mm/s (10-4m/s)

UPSC Civil services Entrance exams General Studies test # General Science Atoms Prepare / Learn

Q5. Find the kinetic, potential, and total energies of the hydrogen atom in the first excited level, and find the wavelength of the photon emitted in a transition from that level to the ground level.

K_{2}

= 3.80 eV, U2 =-6.80 eV and

E_{2}

= -3.40 eV. For the ground level (n = 1)

E_{1}

= -13.6 eV,

λ

= 132 nm

K_{2}

= 3.60 eV,

U_{2}

=-6.80 eV and

E_{2}

= -3.40 eV. For the ground level (n = 1)

E_{1}

= -13.6 eV,

λ

= 129 nm

K_{2}

= 3.40 eV,

U_{2}

=-6.80 eV and

E_{2}

= -3.40 eV. For the ground level (n = 1)

E_{1}

= -13.6 eV,

λ

= 122 nm

K_{2}

= 3.90 eV, U2 =-6.80 eV and

E_{2}

= -3.40 eV. For the ground level (n = 1)

E_{1}

= -13.6 eV,

λ

= 142 nm

Answer : Option C
Explaination / Solution:
No Explaination.

UPSC Civil services Entrance exams General Studies test # General Science National Income and Related Aggregates Prepare / Learn

Q6. Investment in macroeconomics is

A. Updating the stock of capital

B. Division of the stock of capital

C. Reduction in the stock of capital

D. Addition to the stock of capital

Answer : Option D
Explaination / Solution:
No Explaination.

UPSC Civil services Entrance exams General Studies test # General Science Organic compounds containing Nitrogen Prepare / Learn

Q7. In a coupling reaction, the azo products obtained, involve an

A. nuclepholic substitution

B. electrophilic substitution reaction.

C. –N=N– bond

D. –N=N– bond and electrophilic substitution reaction.

Answer : Option D
Explaination / Solution:

In coupling reaction Diazonium salt to act as a electrophile and –N=N- bond forms.

UPSC Civil services Entrance exams General Studies test # General Science Electrostatic Potential and Capacitance Prepare / Learn

Q8. The effective capacitance of two capacitors of capacitances C1 and C2 (with C2 > C1) connected in parallel is 25/6 times the effective capacitance when they are connected in series. The ratio C2/C1 is

A. -4/3

B. -25/6

C. -5/3

D. -3/2