Modern Physics — Part 1 MCQs with Explanations

The fraction of a radioactive substance that remains after a certain time period is given by the formula: Fraction remaining = (1/2)^(time elapsed / half-life) Given that the half-life of the radioactive element is 5 years and we want to find the fraction remaining after 20 years, we substitute these values into the formula: Fraction remaining = (1/2)^(20 / 5) = (1/2)^4 = 1/16 So, after 20 years, only 1/16 of the radioactive substance remains.

A hydrogen atom typically consists of one proton and one electron . Most hydrogen atoms have no neutrons; they only contain a proton in their nucleus. However, hydrogen has isotopes like deuterium and tritium that contain neutrons: Deuterium has one neutron, and Tritium has two neutrons. Since the question is about the standard hydrogen atom, which does not have any neutrons, Option D is correct.

J Robert Oppenheimer is the correct answer to “. . . . . . . . invented Atom Bomb.”. This question is standard in competitive examination syllabi for Modern Physics.

Goldstein is the correct answer to “Positive rays were discovered by”. This question is standard in competitive examination syllabi for Modern Physics.

electron waves is the correct answer to “Cathode rays are”. This question is standard in competitive examination syllabi for Modern Physics.

when high speed electron is obstructed by a metal surface is the correct answer to “X-ray can be produced”. This question is standard in competitive examination syllabi for Modern Physics.

fusion reactions is the correct answer to “Solar energy is due to”. This question is standard in competitive examination syllabi for Modern Physics.

Option "Both A and C" is the correct answer for this question under Modern Physics.

rectifier is the correct answer to “Alternating current is converted into direct current by a”. This question is standard in competitive examination syllabi for Modern Physics.

Graphite is the correct answer to “Which one of the following is used as a moderator in the nuclear reactor”. This question is standard in competitive examination syllabi for Modern Physics.

photon is the correct answer to “The light is composed of small particles, called . . . . . . . .”. This question is standard in competitive examination syllabi for Modern Physics.

nuclear fusion is the correct answer to “Hydrogen bomb is based on”. This question is standard in competitive examination syllabi for Modern Physics.

Energy generation in stars is the correct answer to “Which statement is not associated with nuclear fission”. This question is standard in competitive examination syllabi for Modern Physics.

James Chadwick is the correct answer to “Neutrons were discovered by”. This question is standard in competitive examination syllabi for Modern Physics.

Nuclear fission is the correct answer to “The principle of atomic bomb is based on”. This question is standard in competitive examination syllabi for Modern Physics.

Nuclear fusion of deuterium is the correct answer to “The working principle of atom bomb is nuclear fission of uranium and the working principle of hydrogen bomb is”. This question is standard in competitive examination syllabi for Modern Physics.

Atomic clocks is the correct answer to “Which of the following are used for accurately measuring very small time intervals”. This question is standard in competitive examination syllabi for Modern Physics.

Modulation is the correct answer to “For which diode is used”. This question is standard in competitive examination syllabi for Modern Physics.

fission is the correct answer to “The process by which a heavy nucleus splits into light nuclei is known as”. This question is standard in competitive examination syllabi for Modern Physics.

lead is the correct answer to “The material used for safety from nuclear radiation is”. This question is standard in competitive examination syllabi for Modern Physics.

coherent and monochromatic is the correct answer to “The laser is a beam of radiations which are”. This question is standard in competitive examination syllabi for Modern Physics.

All of these is the correct answer to “Radioactive substance emits”. This question is standard in competitive examination syllabi for Modern Physics.

stability is the correct answer to “The binding energy of nucleus is a measure of its”. This question is standard in competitive examination syllabi for Modern Physics.

U-238 is the correct answer to “Which fuel is used by Nuclear reactors in India”. This question is standard in competitive examination syllabi for Modern Physics.

Photoelectric is the correct answer to “The reverse effect of X-ray emission is”. This question is standard in competitive examination syllabi for Modern Physics.

It seeks to promote the peaceful use of Nuclear energy throughout the world is the correct answer to “What is the main function of the IAEA”. This question is standard in competitive examination syllabi for Modern Physics.

Chain process would go out of bounds is the correct answer to “What happens if the control rods are not used in a nuclear reactor”. This question is standard in competitive examination syllabi for Modern Physics.

Only 1 and 3 is the correct answer to “The atomic power plants are located at 1. Narora 2. Ghatshila 3. Kalpakkam 4. Nangal Select the correct answer:”. This question is standard in competitive examination syllabi for Modern Physics.

Plutonium is the correct answer to “The fuel used in Fast Breeder Test Reactor at Kalpakkam is”. This question is standard in competitive examination syllabi for Modern Physics.

Zirconium is the correct answer to “Which one of the following is not radioactive”. This question is standard in competitive examination syllabi for Modern Physics.

$$\frac{1}{{{\text{decay constant}}}}$$ is the correct answer to “The mean life of a radioactive substance is equal to”. This question is standard in competitive examination syllabi for Modern Physics.

1957 is the correct answer to “In which year was India's first nuclear reactor formally inaugurated by Prime Minister JL Nehru”. This question is standard in competitive examination syllabi for Modern Physics.

Scintillation counter is the correct answer to “Which one of the following can be used to confirm whether drinking water contains a gamma emitting isotope or not”. This question is standard in competitive examination syllabi for Modern Physics.

Fermi is the correct answer to “Which is the most suitable unit for expressing nuclear radius”. This question is standard in competitive examination syllabi for Modern Physics.

ultraviolet rays is the correct answer to “Which of the following types of rays do not enter the Earth's atmosphere”. This question is standard in competitive examination syllabi for Modern Physics.

The speed of the electron will be higher than that of the proton is the correct answer to “An electron and a proton starting from rest are accelerated through a potential difference of 1000 V. Which one of the following statements in this regard is correct”. This question is standard in competitive examination syllabi for Modern Physics.

virtual reality is the correct answer to “A new technology which provides the ability to create an artificial world and have people interact with it is called”. This question is standard in competitive examination syllabi for Modern Physics.

Nuclear fusion is the correct answer to “Source of energy from the Sun is”. This question is standard in competitive examination syllabi for Modern Physics.

1998 is the correct answer to “In which year did India conduct its second nuclear test in Pokhran”. This question is standard in competitive examination syllabi for Modern Physics.

Hydroge is the correct answer to “Nuclear fuel in the sun is-”. This question is standard in competitive examination syllabi for Modern Physics.