General Science Jkssb Chemistry Set 1 Mcqs (504 MCQs) | JKSSB & SSC Quiz

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jkssb chemistry set 1 mcqs

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Practice Questions

504 Total
Question 141 Discuss
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Which element has the highest atomic number and is the heaviest naturally occurring element?

A
Thorium (Th)
B
Uranium (U)
C
Plutonium (Pu)
D
Neptunium (Np)

Answer & Explanation

Correct Option: B

Uranium, boasting an atomic number of 92, is the heaviest element that can be found in appreciable, naturally occurring quantities within the Earth's crust. Elements possessing higher atomic numbers are overwhelmingly synthesized artificially in laboratories or highly specialized nuclear reactors.
Question 142 Discuss
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In 1866, John Newlands, an English scientist, arranged the then known elements in the order of It is known as 'Newlands' Law of Octaves'.

A
decreasing atomic masses
B
decreasing atomic number
C
increasing atomic masses
D
increasing atomic number

Answer & Explanation

Correct Option: C

In 1865-1866, British chemist John Newlands historically attempted to classify the known elements by arranging them in an order of strictly increasing atomic mass. He observed that every eighth element exhibited highly similar properties, famously dubbing this periodic rhythm the 'Law of Octaves.'
Question 143 Discuss
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The Modern Periodic Table has 18 vertical columns known as 'groups' and horizontal rows known as 'periods'.

A
7
B
6
C
8
D
12

Answer & Explanation

Correct Option: A

The modern periodic table is elegantly structured into precisely 7 horizontal periods. These periods visually represent the seven principal quantum energy levels that encapsulate the electrons of all currently discovered and named elements.
Question 144 Discuss
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.........of a substance is the temperature and pressure at which three phases (gas, liquid, and soli(D) of that substance may coexist in thermodynamic equilibrium.

A
Tri-state
B
Amphibious
C
Triple-point
D
Allotropic

Answer & Explanation

Correct Option: C

The triple point of a chemical substance is the unique, precise set of temperature and pressure conditions where its solid, liquid, and gaseous phases exist simultaneously in perfect thermodynamic equilibrium. For example, water's exact triple point is fundamentally used to define the Kelvin temperature scale.
Question 145 Discuss
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Which historical gas law states that the pressure of a given mass of an ideal gas is inversely proportional to its volume at a constant temperature?

A
Charles's law
B
Boyle's law
C
Gay-Lussac's law
D
Avogadro's law

Answer & Explanation

Correct Option: B

Formally published in 1662, Boyle's Law mathematically describes the inverse relationship between the volume and pressure of a gas when the temperature is rigidly held constant (P ∝ 1/V). It was one of the earliest quantitative physical laws discovered in the history of chemistry.
Question 146 Discuss
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At absolute zero ( 0 K or −273.15∘C ), the particles of matter:

A
Vibrate in fixed positions
B
Stop moving
C
Move at the speed of light
D
Undergo fusion

Answer & Explanation

Correct Option: B

In classical thermodynamics, absolute zero (0 K) represents the lowest theoretical limit of temperature, where all thermal motion of particles effectively ceases. While quantum mechanics dictates they still retain a tiny 'zero-point energy,' macroscopic kinetic movement completely stops.
Question 147 Discuss
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Non-metals, are electronegative. They tend to form bonds by electrons.

A
subtracting two
B
gaining
C
substituting
D
losing

Answer & Explanation

Correct Option: B

Non-metals typically possess a high effective nuclear charge and a nearly full valence shell, making them highly electronegative. Consequently, they achieve a highly stable noble-gas configuration by strongly attracting and gaining electrons to form covalent or ionic bonds.
Question 148 Discuss
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When Mendeleev started his work, how many elements were known at that time?

A
56
B
61
C
63
D
72

Answer & Explanation

Correct Option: C

When Dmitri Mendeleev formally presented his groundbreaking periodic table to the Russian Chemical Society in exactly 1869, there were only 63 known elements. He boldly left strategic gaps for undiscovered ones, correctly assuming the list was incomplete.
Question 149 Discuss
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........is a form of matter in which many of the electrons wander around freely among the nuclei of the atoms.

A
Plasma
B
Solid
C
Liquid
D
Gas

Answer & Explanation

Correct Option: A

Plasma, often referred to as the fourth state of matter, is a highly energized, superheated gas consisting of positive ions and free-floating electrons. It is definitively the most abundant state of ordinary matter in the universe, comprising the sun and other massive stars.
Question 150 Discuss
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Which of the following gases, when cooled and compressed, can change from a gas to a supercritical fluid state?

A
Steam
B
Carbon dioxide (CO2)
C
Hydrogen (H2)
D
Oxygen (O2)

Answer & Explanation

Correct Option: B

Carbon dioxide (CO2) is widely used in industry as a supercritical fluid because its critical temperature (31.1°C) and critical pressure are relatively easy to achieve. In this state, it acts as a highly effective, environmentally friendly solvent for decaffeinating coffee and extracting essential oils.
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