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 111 Discuss
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The amount of dissolved oxygen in water becomes lowest at what time of the day?

A
In the dawn
B
In the evening
C
At night time
D
In the afternoon

Answer & Explanation

Correct Option: A

Dissolved oxygen levels universally hit their lowest point just before dawn because aquatic plants and algae consume oxygen through respiration all night without replacing it. Once the sun rises, photosynthesis resumes, and the dissolved oxygen levels slowly begin to increase.
Question 112 Discuss
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The IUPAC name of CH3 −(CH2)18 − CH3 is .

A
decane
B
icosane
C
triacontane
D
dodecane

Answer & Explanation

Correct Option: B

Under the stringent IUPAC nomenclature rules, an unbranched alkane containing exactly 20 carbon atoms is designated as icosane. The formula provided mathematically represents a continuous, fully saturated hydrocarbon chain of C20H42.
Question 113 Discuss
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Which inorganic compound is known to undergo solid state reaction to form urea?

A
Ammonium phosphate
B
Ammonium cyanate
C
Ammonium acetate
D
Ammonium nitrate

Answer & Explanation

Correct Option: B

In 1828, Friedrich Wöhler historically synthesized urea, an organic compound, by simply heating the inorganic salt ammonium cyanate. This landmark discovery helped disprove 'vitalism,' the prevailing scientific belief that organic compounds could only be produced by living organisms.
Question 114 Discuss
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What is the percentage of 's' character in the carbon atom of acetylene?

A
75%
B
25%
C
50%
D
33.33%

Answer & Explanation

Correct Option: C

The carbon atoms within acetylene undergo sp hybridization to form their rigidly linear triple bond structure. Since this hybrid orbital is constructed equally from one 's' and one 'p' orbital, it possesses exactly 50% 's' character.
Question 115 Discuss
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Helium gas can be converted to the liquid form by the .

A
dipole-dipole forces of attraction
B
London forces of attraction
C
dipole-induced dipole forces of attraction
D
hydrogen bonding interaction

Answer & Explanation

Correct Option: B

Helium is a noble gas featuring perfectly non-polar, isolated atoms, meaning it completely lacks permanent dipoles. It can only be liquefied at temperatures near absolute zero when extremely weak, temporary London dispersion forces become sufficient to hold the slow-moving atoms together.
Question 116 Discuss
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What is the chemical formula for butane?

A
C4H8
B
C2H10
C
C2H6
D
C4H10

Answer & Explanation

Correct Option: D

Butane is a straightforward alkane, which adheres chemically to the general molecular formula CnH2n+2. Since the 'but-' prefix definitively signifies four carbon atoms, the proper structural formula for butane is C4H10.
Question 117 Discuss
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What is the correct way to mix acid and water?

A
The water must be added to the acid.
B
The water must be heated before mixing.
C
The acid must be heated before mixing.
D
The acid must be slowly added to the water.

Answer & Explanation

Correct Option: D

Mixing a strong acid with water is an intensely exothermic process that releases significant heat. Acid must always be poured slowly into a larger volume of water to dissipate the heat safely, whereas adding water directly to acid can cause dangerous, explosive boiling and splashing.
Question 118 Discuss
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What is the number of protons present in beryllium.

A
2
B
6
C
8
D
4

Answer & Explanation

Correct Option: D

Beryllium is explicitly defined as the fourth element positioned on the periodic table, meaning its atomic number is precisely 4. Consequently, every beryllium atom inherently possesses exactly 4 positively charged protons in its nucleus.
Question 119 Discuss
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Identify the number of electrons found in the outermost shell of halogen.

A
7
B
5
C
8
D
6

Answer & Explanation

Correct Option: A

Halogens, such as fluorine and chlorine, all reside within Group 17 of the periodic table. They are defined chemically by possessing exactly 7 valence electrons in their outermost electron shell, making them highly reactive as they seek one additional electron to achieve a stable octet.
Question 120 Discuss
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The tendency of an atom or a functional group to attract a shared pair of electrons toward itself, is known as:

A
electronegativity
B
electron affinity
C
electro-positivity
D
electro attraction

Answer & Explanation

Correct Option: A

Electronegativity was famously conceptualized by Linus Pauling in 1932 to describe an atom's inherent ability to attract shared electrons within a covalent bond. High electronegativity results in polarized chemical bonds where electrons are physically pulled closer to the more electronegative atom.
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