The mass of 1mole mg 12 if do how many grams of mg are there in 36 grams mg
Answers
Answer:
Q. No. 1 Which of the following contains equal to those in 12g Mg? (At. Wt. Mg = 24)
Option 1 12 gm C
Option 2 7 gm N2
Option 3 32 gm O2
Option 4 None of these
Correct Answer 2
Explanation 12 1 Moles of Mg = = 24 2
1 Atoms = N
2
A
7 1 Moles of N = =
28 4 2
1 N No of atoms = N 2=
4 2
A
A
Q. No. 2
If moles of oxygen combine with Al to form Al O ,the weight of Al used in 1
1 he
2
t 2 3
reaction is (Al = 27)
Option 1 27 g
Option 2 54 g
Option 3 40.5 g
Option 4 81 g
Correct Answer 2
Explanation 3
2Al+ O Al O
2
2 2 3
3
2 mole mole
2
For mole of O , moles of Al required is 2
2
e
3 mol 2
at = 2 27 = 54gm
Q. No. 3 Which has the highest mass?
Option 1 50 g of iron
Option 2 5 moles of N2
Option 3 0.1 mol atom of Ag
Option 4 1023 atoms of carbon
Correct Answer 2
Explanation 50 gm Fe
5 moles N = 5 28 = 140gm 2
1 mole Ag = 0.1 108 = 10.8 gm
10 1 10 atomof C = moles = moles
6.022 10 6.022
23
23
23
1
= 12= 2 gm
6.022
Q. No. 4 The number of atoms present in 0.5 mole of nitrogen is same as the atoms in
Option 1 12 g of C
Option 2 64 g of S
Option 3 8 g of O
Option 4 48 g of Mg
Correct Answer 1
Explanation 0.5 mole N contains 0.5 N molec e ul s 2 A
= 0.5 N 2 = N atom A A
This is same for 12 gm of C
Q. No. 5 Which of the following weighs the least?
Option 1 2 g atom of N (at. wt. of N = 14)
Option 2 3 10 atoms of C (at. wt of C = 12) 23
Option 3 1 mole of S (at. wt. of S = 32)
Option 4 7 g silver (at. wt. of Ag = 108)
Correct Answer 2
Explanation 2 gm atom of N 28 gm
3 10 1 3 10 atomof C = = moles
6 10 2
23
23
23
1
= 12=6gm
2
1 mole of S = 32 gm
7 gm Ag
Q. No. 6 If NA is Avogadro’s number then number of valence electrons in 4.2 g of nitride ions
(N3–
) is
Option 1 2.4 NA Option 2 4.2 NA Option 3 1.6 NA Option 4 3.2 NA Correct Answer 1
Explanation 4.2 Moles = = 0.3
14
0.3 mole contains 0.3 NA ions
One ion has 8 valence electron : total valence electron = 0.3NA A 8 = 2.4 N
Q. No. 7 Hemoglobin contains 0.33 % of iron by weight. The molecular weight of hemoglobin is
approximately 67200. The number of iron atoms (at. wt. of Fe = 56) present in one
molecule of hemoglobin is
Option 1 6
Option 2 1
Option 3 4
Option 4 2
Correct Answer 3
Explanation 100 gm of Haemoglobin contains 0.33 gm of iron. Let there are x atoms of iron present
in one molecule.
100 1 Moles of Haemoglobin= = 67200 672
0.33 Moles of Fe = = 4
672 56
x
x
Q. No. 8 The number of molecules in 4.25 g of ammonia is about
Option 1 1.0 10
23
Option 2 1.5 10
23
Option 3 2.0 10
23
Option 4 2.5 10
23
Correct Answer 2
Explanation 4.25 Moles = = 0.25
17
No. of molecules = 0.25 6.023 1023
= 1.5 10
23
Q. No. 9 If 20% nitrogen is present in a compound, its minimum molecular weight can be
Option 1 144
Option 2 28
Option 3 100
Option 4 70
Correct Answer 4
Explanation For minimum molecular weight 1 mole of compound must contain 1 mole of atom.
Moles of compound = Moles of atom
100 20 = M= 70
M 14
Q. No. 10 The weight of molecule of the compound C60H122 is
Option 1 1.4 10 g
-21
Option 2 1.09 10 g
-21
Option 3 5.025 10 g
23
Option 4 16.023 10 g
23
Correct Answer 1
Explanation (6 wt
0
o
1
f on 2+12 e molecu 2 1) = gm
6. 0
l
022
e
1
23
=1.4 10 gm
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