Periodic Classification Of Elements(10th Grade > Chemistry ) Questions and answers for exam Preparation

10th Grade > Chemistry

PERIODIC CLASSIFICATION OF ELEMENTS MCQs

Total Questions : 54 | Page 2 of 6 pages

Question 11. How many elements were discovered till the time when Mendeleev made the periodic table?

Discuss Question

Answer: Option B. -> 63
:
B
When Mendeleev made the periodic table the number of elements discovered till then were 63. Rest were discovered later, and were added consecutively.

Question 12. What will be the mass of Carbon dioxide made from

_{6}^{14} C

Discuss Question

Answer: Option B. -> 46u
:
B
The molecular formula of carbon dioxide is

C O_{2}

.
Molecular mass of

C O_{2}

made from

_{6}^{14} C = 14 + (16 + 16) = 46 u

Question 13. An element X is in the

1^{s t}

group of the modern periodic table. Its ion will be represented as:

X+
X2+
X−
X2−

Discuss Question

Answer: Option A. -> X+
:
A
The elements in the

1^{s t}

group of the periodic table have only one valence electron. Thus, they will tend to lose only one electron to gain the the nearest noble gas configuration.
So, valency of the elements in the

1^{s t}

group of the modern periodic table is 1 and they will lose one electron to form unipositively charged ion,

(A^{+})

Question 14. Isotopes differ in:

Physical properties
Chemical properties
No of protons
No of electrons

Discuss Question

Answer: Option A. -> Physical properties
:
A

Since isotopes have same number of protons and electrons but different number of neutrons, they differ onlyin physical properties and not in chemical properties.

Question 15. The first alkali metal in the modern periodic table is:

Hydrogen
Lithium
Sodium
Francium

Discuss Question

Answer: Option B. -> Lithium
:
B
Alkali metals are the elements in the

1^{s t}

group of the periodic table other than hydrogen. The first alkali metal in the modern periodic table is lithium (Li).

Question 16. In the modern periodic table, the elements are arranged on the basis of their increasing:

Atomic mass
Atomic number
Charge on their ions
Mass number

Discuss Question

Answer: Option B. -> Atomic number
:
B
Elements, when arranged in order of increasing atomic number, lead us to the classification known as the modern periodic table. The chemical and physical properties of the elements vary periodically when the elements are arranged in the order of their atomic numbers.

Question 17. Which of the following is a Dobereiner's triad?

Ne, Ca, Na
H2,N2,O2
Li, Na, K
Cl, Na, Ca

Discuss Question

Answer: Option C. -> Li, Na, K
:
C
According to Dobereiner's law of triads, the atomic mass of the middle element of a triad is equal to the arithmetic mean of the atomic masses of the other two elements.
Inthe triad of lithium, sodium and potassium.The atomic mass of lithium is 7 andthe atomic mass of potassium is 39. The arithmetic mean of atomic masses of lithium and potassium gives atomic mass of sodium i.e. 23.

Question 18. No. of neutrons present in

_{92}^{238} Ur

are:

Discuss Question

Answer: Option B. -> 146
:
B
Number of neutrons = Mass No. - Atomic No.
Since 238 is the mass number,
No. of neutrons = 238 - 92 = 146

Question 19. Which of the following elements does not lose an electron easily?

Discuss Question

Answer: Option B. -> F
:
B
Elements try to attain the nearest noble gasconfiguration by losing or gaining electrons.
Fluorine has 7 electrons in its outer shell. These 7 electrons are bound tightly by the nucleus. It has a tendency to gain an electron to achieve the nearest noble gasconfiguration.
However,Na, Mg and Altend tolose electrons to acheive the nearest noble gasconfiguration.

Question 20. Which of the following is an alkaline earth metal?

11Na
12Mg
19K
13Al

Discuss Question

Answer: Option B. -> 12Mg
:
B
Alkaline earthelements are elements found in the second group of the periodic table. These elements have two valence electrons.
In the given options magnesium