SPSC Lecturer Chemistry Past Paper 2000 to till date

Q61: Which of the following transitions are NOT allowed in the normal electronic emission spectrum of an atom?

ایٹم کے عام الیکٹرانک اخراج اسپیکٹرم میں مندرجہ ذیل میں سے کون سے ٹرانزیشن کی اجازت نہیں ہے؟

2p → 1s

2s → 1s

3d → 2p

None of these

Q62: The maximum number of electrons in sub energy level I = 3 are _____?

14

32

18

None of these

Q63: If the wave length of photon is doubled _____?

اگر فوٹوون کی لہر کی لمبائی دوگنی ______ ہے؟

Energy is doubled

Frequency is doubled

Energy is reduced by the factor of two

None of these

Explanation

Energy of a photon is given by $E = frac{hc}{lambda}$ , so if the wavelength ( $lambda$ ) is doubled, energy ( $E$ ) is halved.

Frequency ( $f$ ) and wavelength ( $lambda$ ) are inversely related ( $c = flambda$ ), so doubling $lambda$ reduces $f$ by half.

Q64: The melting point of mercury is ______?

عطارد کا پگھلنے کا نقطہ ______ ہے؟

-39°C

0°C

-100°C

None of these

Q65: Which substance is known as Oil of Vitriol?

کون سا مادہ وٹریول کے تیل کے نام سے جانا جاتا ہے؟

Nitric acid

Hydrochloric acid

Phosphoric acid

Sulfuric acid

Q66: To be at daggers drawn means _____?

Complete Agreement

Bitter Enmity

Strong Friendship

None of these

Q67: Which of the following instruments may be used to measure the optical activity of a compound?

کسی کمپاؤنڈ کی آپٹیکل سرگرمی کی پیمائش کے لئے مندرجہ ذیل میں سے کون سا آلات استعمال ہوسکتے ہیں؟

Polarimeter

Spectrophotometer

Calorimeter

None of these

Q68: Which of the following instrumental component is not required in atomic emission spectrometer?

جوہری اخراج اسپیکٹومیٹر میں مندرجہ ذیل میں سے کون سا آلہ کار جزو کی ضرورت نہیں ہے؟

Monochromator

Source of electromagnetic radiation

Detector

None of these

Q69: A system of government by the wealthy is called _____?

Democracy

Plutocracy

Aristocracy

None of these

Q70: A gas is said to behave like an ideal gas when relation PV/T= Constant. When do you expect a real gas to behave like ideal gas?

When the temperature is high and pressure is low

When the temperature is low

When both the temperature and pressure are low

None of these

Explanation

A real gas behaves like an ideal gas at high temperature (molecules have enough kinetic energy to overcome intermolecular forces) and low pressure (molecules are far apart, reducing interactions).

Under these conditions, the gas follows the ideal gas equation $PV = nRT$ .