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General ScienceEasyAsked in: CDS · CDS-I 2025, GK

The force with which the Earth attracts an object is called:

  1. A.Weight of the object
  2. B.Mass of the object
  3. C.Density of the object
  4. D.Magnitude of the object

Correct answer

A. Weight of the object

Explanation

The correct answer is A, Weight of the object. Weight is the gravitational force with which the Earth pulls an object towards its centre.

Weight is given by W = mg, where m is the mass and g is the acceleration due to gravity, about 9.8 m/s² near the Earth's surface. Because it is a force, weight is a vector, it acts towards the centre of the Earth and its SI unit is the newton. Weight changes from place to place: it is slightly more at the poles than at the equator, it falls as one goes higher, and on the Moon it is about one-sixth of its value on Earth. It is measured with a spring balance.

B is wrong because mass is the amount of matter in a body, measured in kilograms, and stays the same everywhere. C is wrong because density is mass per unit volume, a property of the material, not a force. D is wrong because magnitude only means the size of a quantity and is not the name of any force.

Exam tip: mass is constant, in kilograms, and measured by a beam balance; weight is mg, in newtons, and measured by a spring balance.

Practice Questions

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Q1.General ScienceAsked in: UPSC Civil Services · CSE Prelims 2022, GS Paper IMedium

Which of the following are nitrogen-fixing plants?

1. Alfalfa

2. Amaranth

3. Chickpea

4. Clover

5. Purslane (Kulfa)

6. Spinach

Select the correct answer using the code given below:

  1. A.1, 3 and 4 only
  2. B.1, 3, 5 and 6 only
  3. C.2, 4, 5 and 6 only
  4. D.1, 2, 4, 5 and 6
Show answer
Correct answer: A. 1, 3 and 4 only

Alfalfa, chickpea and clover are legumes, and legumes fix nitrogen. Plants of the legume family (Fabaceae) carry root nodules that house Rhizobium bacteria.

Q2.General ScienceAsked in: UPSC CAPF · CAPF 2017, Paper IMedium

The mass number of an element is NOT changed when it emits

  1. A.Alpha and Beta radiations only
  2. B.Alpha and Gamma radiations only
  3. C.Beta and Gamma radiations only
  4. D.Alpha, Beta and Gamma radiations
Show answer
Correct answer: C. Beta and Gamma radiations only

Neither beta nor gamma emission changes the total number of protons and neutrons in a nucleus, so the mass number stays the same.

Q3.General ScienceAsked in: UPSC CAPF · CAPF 2025, Paper IMedium

Which one among the following statements about facilitated transport in plants is correct?

  1. A.All passive transports are types of facilitated transport.
  2. B.Facilitated transport is an example of active transport.
  3. C.Water moves across plasma membrane by active transport.
  4. D.Facilitated transport requires assistance of carrier proteins.
Show answer
Correct answer: D. Facilitated transport requires assistance of carrier proteins.

In facilitated transport, molecules cross the membrane with the help of membrane proteins, while still moving down their concentration gradient.

Q4.General ScienceAsked in: UPSC CAPF · CAPF 2017, Paper IMedium

Who among the following has coined the term 'Quark', the fundamental particles that make up protons and neutrons in an atomic nucleus ?

  1. A.Richard Feynman
  2. B.Murray Gell-Mann
  3. C.Albert Einstein
  4. D.Niels Bohr
Show answer
Correct answer: B. Murray Gell-Mann

The American physicist Murray Gell-Mann proposed quarks in 1964 and gave them their name. Gell-Mann, and independently George Zweig, suggested that protons, neutrons and other such particles are built from smaller units.