CBSE Class 12 Biology, Physics, Chemistry: Important Questions|CBSE Term 2 Board Exam 2021-22

Tulika Tandon

Updated: May 23, 2022 14:07 IST

CBSE students who are in Class 12th and have opted for the Science stream can check the list of questions below to get an idea of the question paper. 

Term 2 CBSE Class 12th Important Questions: Science (Physics, Chemistry, Biology) 

CBSE (Term 2) Class 12th Physics: Important Questions 

Q. 

(a) Name the e.m. waves that are suitable for radar systems used in aircraft navigation. Write the range of frequency of these waves.

(b) If the Earth did not have an atmosphere, would its average surface temperature be higher or lower than what it is now? Explain.

(c) An e.m. wave exerts pressure on the surface on which it is incident. Justify. 

Ans. 

(a) Microwaves are suitable for the radar system used in aircraft navigation. The range of frequency of microwaves is 108 Hz to 1011 Hz.

(b) If the Earth did not have an atmosphere, then there would be an absence of the greenhouse effect of the atmosphere. Due to this reason, the temperature of the earth would be lower than what it is now. 

(c) An e.m. wave carries momentum with itself and is given by

P = Energy of wave(U)/ Speed of the wave(c) = U/c

when it is incident upon a surface it exerts pressure on it. 

Check more important questions for Physics Class 12th here. 

CBSE (Term 2) Class 12th Chemistry: Important Questions 

Q. Account for the following:

Ti(IV) is more stable than Ti (II) or Ti(III).

In the case of transition elements, ions of the same charge in a given series show a progressive decrease in radius with increasing atomic number.

Zinc is a comparatively soft metal, iron and chromium are typically hard.

Ans. 

(a) Ti is having electronic configuration [Ar] 3d2 4s2. Ti (IV) is more stable as Ti4+ acquires the nearest noble gas configuration on the loss of 4 e-.

(b) In the case of transition elements, ions of the same charge in a given series show a progressive decrease in radius with increasing atomic number. As the new electron enters a d orbital each time the nuclear charge increases by unity. The shielding effect of a d electron is not that effective, hence the net electrostatic attraction between the nuclear charge and the outermost electron increases and the ionic radius decreases.

(c) Iron and Chromium are having a high enthalpy of atomization due to the presence of unpaired electrons, which accounts for their hardness. However, zinc has a low enthalpy of atomization as it has no unpaired electrons. Hence zinc is comparatively a soft metal. 

Check more important questions for Chemistry Class 12th here. 

CBSE (Term 2) Class 12th Biology: Important Questions 

Q. How do normal cells get transformed into cancerous neoplastic cells? Elaborate giving three examples of the inducing agent.

OR

A person is suffering from a high-grade fever. Which symptoms will help to identify if he/she is suffering from Typhoid, Pneumonia or Malaria? 

Ans. 

The transformation of normal cells into cancerous neoplastic cells may be induced by the following physical, chemical or biological agents causing DNA damage:

Ionising radiations like X-rays and gamma rays

Non-ionizing radiations like UV.

Chemical carcinogens present in tobacco smoke

Cellular oncogenes (c-onc) or proto-oncogenes, when activated under certain conditions cause cancer. Viruses with oncogenes can transform normal cells into cancerous cells.

OR

If the person has sustained a high fever (39° to 40°C), weakness,

stomach pain, constipation, headache and loss of appetite, it is Typhoid.

If the person has fever, chills, cough and headache; and the lips and fingernails turn grey to bluish, it is Pneumonia. 

If the person has chills and a high fever recurring every three to four days then, it is Malaria.

Check more important questions for Biology Class 12th here.