Direction: In the following questions, a statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as:
(a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
(b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of
Assertion (A).
(c) Assertion (A) is true but Reason (R) is false.
(d) Assertion (A) is false but Reason (R) is true
1.) Assertion: Lithium and Sodium both belong to same group.
Reason: Lithium and sodium both have same atomic number.
Answer – (c) Assertion is true but the Reason is false.
2.) Assertion: K shell of an atom can accommodate maximum 2 electrons.
Reason: K shell is always the outermost shell of an particular atom.
Answer – (c) Assertion is true but the Reason is false.
3.) Assertion: Elements having same number of valence shell are placed in same group.
Reason: In a group metallic character increases from Upper to Lower.
Answer – (b) The Assertion and the Reason are correct but the Reason is not the
correct explanation of the Assertion.
4.) Assertion: In a period as we move from left to right nature of oxides gradually changes from basic to acidic.
Reason: On moving left to right in a period non metallic character increases.
Answer – (a) Both the Assertion and the Reason are correct and the Reason is the
correct explanation of the Assertion.
5.) Assertion: The term atomic size refers to the radius of an atom.
Reason: Atomic size depends on – number of protons present in an atom.
Answer – (c) Assertion is true but the Reason is false.
6) Assertion (A) : Mendeléev concentrated on the compounds formed by elements with oxygen and hydrogen in his periodic table.
Reason (R) : Hydrogen and oxygen are very reactive and form compounds with most elements.
Answer(a)
7)Assertion (A) : In Mendeléev Periodic Table, cobalt was placed before nickel.
Reason (R): The atomic mass of cobalt is less than nickel.
Answer(c)
8) Assertion (A) : According to Mendeléev, the properties of elements are a periodic function of their atomic masses.
Reason (R) : Atomic number is equal to the number of protons.
Answer(b)
9) Assertion (A) : Noble gases have zero valency.
Reason (R) : Noble gases have stable electronic configuration.
Answer(a)
10) Assertion (A) : Elements in the same vertical column have similar properties.
Reason (R) : Elements have periodic dependence upon the atomic number.
Answer(b)
11) Assertion (A) : Silicon is a metalloid.
Reason (R) : Silicon shows only properties of non-metals.
Answer(c)
12) Assertion (A) : Fluorine has greater atomic radius than nitrogen.
Reason (R): Atomic radius decreases along a period.
Answer(d)
13) Assertion (A): Li, Na, K form Döbereiner’s triads.
Reason (R) : Atomic mass of Na is roughly the average of atomic masses of Li and K.
Answer(a)
14) Assertion (A) : Magnesium belongs to 3rd period of modern periodic table.
Reason (R) : The valence electrons of magnesium is 2.
Answer(b)
15) Assertion (A) : Isotopes are placed together in the modern periodic table.
Reason (R) : Isotopes have same atomic number.
Answer(a)
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