Revision Series | Science | General Science | 33

November 15, 2023

Which of the following phenomena are caused by the scattering of light?
1. The colour of clear sky is blue.
2. Twinkling of the stars.
3. The colour of the Sun at Sunrise and Sunset is red.

(A) 1 and 2 only
(B) 1, 2 and 3
(C) 2 and 3 only
(D) 1 and 3 only

Show Answer

Answer- D

The sky appears blue during a clear cloudless day because the molecules in the air scatter blue light from the sun more than they scatter red light. Twinkling of stars is caused by the atmospheric refraction of light. Light from the sun near the horizon passes through thicker layers of air and travel larger distance in the earth’s atmosphere before reaching our eyes. Near the horizon, most of the blue light and other lights with shorter wavelengths are scattered away by the particles. Therefore, the light that reaches our eyes is of longer wavelength. This gives rise to the reddish appearance of the Sun.

Which of the following assertions is/are correct?
1. The liver is the largest gland in the body.
2. The liver does not secrete bile juice.
3. Bile juice plays an important role in the digestion of fat.
Use the code given below to select the correct answer —

(A) 2 only
(B) 1 and 3 only
(C) 2 and 3 only
(D) 1, 2 and 3

Show Answer

Answer- B

Production of bile, which helps carry away waste and break down fats in the small intestine during digestion.
Production of certain proteins for blood plasma.
Production of cholesterol and special proteins to help carry fats through the body
Conversion of excess glucose into glycogen for storage (glycogen can later be converted back to glucose for energy) and to balance and make glucose as needed
Regulation of blood levels of amino acids, which form the building blocks of proteins
Processing of hemoglobin for use of its iron content (the liver stores iron)
Conversion of poisonous ammonia to urea (urea is an end product of protein metabolism and is excreted in the urine) Clearing the blood of drugs and other poisonous substances
Regulating blood clotting · Resisting infections by making immune factors and removing bacteria from the bloodstream
Clearance of bilirubin, also from red blood cells. If there is an accumulation of bilirubin, the skin and eyes turn yellow.

Which of the following is/are necessary for photosynthesis?
1. Chlorophyll
2. Sunlight
3. Carbon dioxide
4. Water
Use the code given below to select the correct answer —

(A) 1 and 2 only
(B) 1, 2 and 3 only
(C) 3 and 4 only
(D) 1, 2, 3 and 4

Show Answer

Answer- D

Leaves have a green pigment called chlorophyll. It helps leaves to capture the energy of sunlight. This energy is used to synthesise (prepare) food from carbon dioxide and water. Since the synthesis of food occurs in the presence of sunlight, it is called photosynthesis (Photo: light; synthesis: to prepare). So, chlorophyll, sunlight, carbon dioxide and water are necessary to carry out the process of photosynthesis.

Regarding blood pressure, consider the following statements:
1. The Blood pressure is higher in Veins than in Arteries.
2. The normal systolic pressure is about 120 mm of Hg and diastolic pressure is 80 mm of Hg.
3. Blood pressure is measured with an instrument called sphygmomanometer.
Which of the statements given above is/are correct?

(A) 1 and 2 only
(B) 2 and 3 only
(C) 3 only
(D) 1, 2 and 3

Show Answer

Answer- B

The force that blood exerts against the wall of a vessel is called blood pressure.
This pressure is much greater in arteries than in veins as arteries carry oxygenated blood from heart to other parts of body that emerge at high pressure and remains in the same.
The pressure of blood inside the artery during ventricular systole (contraction) is called systolic pressure and pressure in artery during ventricular diastole (relaxation) is called diastolic pressure.
The normal systolic pressure is about 120 mm of Hg and diastolic pressure is 80 mm of Hg. Blood pressure is measured with an instrument called sphygmomanometer.

What is the SI unit of Resistance?

(A) Volt
(B) Coulomb
(C) Ampere
(D) ohm

Show Answer

Answer- D

The dark lines in the solar spectrum are due to

(A) Absorption of corresponding wavelengths by the outer layers of the sun.
(B) Destructive interference between waves of certain definite wavelengths.
(C) Absorption of corresponding wavelengths by the prism used in the photograph.
(D) Absence of corresponding wavelengths from the light emitted by the core of the sun

Show Answer

Answer- A

Which of the following use convex mirror?
1. Torches
2. Vehicles headlights
3. Dentists to see larger images of the patient's teeth.
4. Shaving mirror
Select the correct answer using the code given below:

(A) 1 and 2 only
(B) 2, 3 and 4 only
(C) 1, 3 and 4 only
(D) None of the above

Show Answer

Answer- D

Concave mirrors are commonly used in torches, searchlights and vehicles headlights to get powerful parallel beams of light as these mirrors possess the ability to focus parallel rays of light to a point, produce a large size image.
They are often used as shaving mirrors to see a larger image of the face The dentists use concave mirrors to see large images of the teeth of patients. Large concave mirrors are used to concentrate sunlight to produce heat in solar furnaces

Which of the following is a highly reactive metal which catches fire when exposed to air?

(A) Phosphorus
(B) Sodium
(C) Iodine
(D) Bromine

Show Answer

Answer- B

Phosphorus, Iodine and Bromine are all non-metals. They do not generally react with water, but are highly reactive in air. Of the three, phosphorus is the most reactive non-metal. It catches fire on being exposed to air.
To prevent the contact of phosphorus with atmospheric oxygen, it is stored in water. Bromine is the only non- metal which exists as a liquid in room temperature.
Sodium is a metal which is highly reactive in nature. It reacts rapidly with air and water. A lot of energy is generated in these reactions. Therefore, it is stored in kerosene oil.

Regarding amoeba, consider the following assertions:
1. It is a microscopic single-celled organism found in pond water.
2. Amoeba constantly changes its shape and position. 3. Amoeba has a cell membrane, a rounded, dense nucleus and many small bubble-like vacuoles in its cytoplasm
Which of the above assertions is/are correct?

(A) 1 and 2 only
(B) 2 and 3 only
(C) 3 only
(D) 1, 2 and 3

Show Answer

Answer- D

1. Cell membrane – the thin layer of protein and fat that surrounds the amoeba; it allows some substances to pass into the cell, and blocks other substances.
2. Contractile vacuole – a cavity within the amoeba that excretes excess water and waste; the waste is brought to the cell membrane and is then eliminated from the amoeba.
3. Cytoplasm (ectoplasm and endoplasm) – a jelly-like material that fills most of the cell; the
organelles (like the nucleus) are surrounded by cytoplasm.

Which of the following does not match the characteristics of an Isotope?

(A) Isotopes of some elements are radioactive
(B) Isotopes are the atoms of different elements
(C) Isotopes differ in number of neutrons
(D) Isotopes have similar chemical properties

Show Answer

Answer- B.

Elements with the same atomic number but a different mass number are defined as “Isotopes”.

The number of protons and neutrons combined together is called atomic mass or mass number of an element, whereas the total number of protons gives the atomic number of an element.

In a certain element, the number of protons will always remain constant. However, the number of neutrons can change.

The number of neutrons varies but the number of protons always remains same in an isotope of a single element.

”For Example: Hydrogen has three most stable isotopic forms- protium, deuterium, as well as tritium. All the three isotopic forms of hydrogen have the same number of protons but vary in the number of neutrons.