Some Basic Concepts of Chemistry Test

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Some Basic Concepts of Chemistry Test - 29

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Weekly Quiz Competition

Question 1
1 / -0

A compound was found to contain 5.37% nitrogen. What is the minimum molecular weight of compound?

A
26.07

B
2.607

C
260.7

D
None of these

Solution

5.37 9 N is present in 100 9 compound
14gN =$$\frac {100 \times 14}{5.37}=260.7 $$g compound (i.e., minimum molecular weight as it should have atleast one N).
Question 2
1 / -0

A chemical equation is balanced in accordance with the law of

A
conservation of mass

B
multiple proportion

C
constant proportion

D
reciprocal proportion

Solution

There must be the same number of each element on both side of the chemical equation. It adheres with the conservation of mass.
Option $$A$$ is correct.
Question 3
1 / -0

A sample of $$CaCO_3$$ has $$Ca=40\%,\,C=12\%$$ and $$O=48\%$$. If the law of constant proportion is true then the weight of $$Ca$$ in $$16\;g$$ of $$CaCO_3$$ made from different processes will be

A
$$64\;g$$

B
$$0.64\;g$$

C
$$6.4\;g$$

D
$$4.6\;g$$

Solution

Gram Molecular Mass of $$CaCO_3$$
$$=40+12+16\times3=40+12+48=100\;gm$$
$$100\;gm\;CaCO_3$$ contain $$=40\;g\;Ca$$
$$\therefore\;16\;g\;CaCO_3$$ will contain $$=\displaystyle\frac{40}{100}\times16=6.4\;g\;Ca$$
Question 4
1 / -0

A sample of $$CaCO_3$$ has Ca =40%, C = 12% and O = 48% by mass. If the law of constant proportion is true then the weight of Ca in 16g of $$CaCO_3$$ made from different processes will be -

A
64 g

B
0.64g

C
6.4g

D
4.6 g

Solution

Molecular weight of $$CaCO_3$$ = 100g
Percentage of Ca = 40 %
Let, law of constant proportion is true.

So, mass of Ca in 100 g of $$CaCO_3$$ = $$\dfrac{40}{100} \times 100 = 40g$$

So, weight of Ca in 16g of $$CaCO_3 $$ = $$\dfrac{40}{100} \times 16g = 6.4g$$
Question 5
1 / -0

Three containers A, B and C of equal volume, contain $$N_2$$, $$NO_2$$ and $$CO_2$$ respectively, at the same temperature and pressure. The ascending order of their masses is:

A
A, C, B

B
C, A, B

C
B, C, A

D
C, B, A

Solution

Since the ideal gas equation is same for all the gases, there will be same number of moles of each gas. Hence, the ascending order of their masses is the ascending order of their molecular weight.
Molecular weight of $${ N }_{ 2 }=$$ 28
Molecular weight of $${ NO }_{ 2 }=$$ 46
Molecular weight of $${ CO }_{ 2 }=$$ 44
Hence, the correct order would be A, C, B .
Question 6
1 / -0

A sugar solution contains $$15\%$$ sugar by weight. When the solution is heated, $$40\%$$ sugar is left in the solution. The amount of water which is disappeared is:

A
$$0.0625\;g$$

B
$$62.5\;g$$

C
$$0.625\;g$$

D
$$6.25\;g$$

Solution

Let the mass of solution $$=100\;g$$
Mass of sugar $$=15\;g$$
Mass of water $$=100-15=85\;g$$
On heating some amount water is disappeared and let the new amount of solution is $$(X)\;g$$, which contain $$40\%$$ sugar equal to $$15\;g$$
$$X\times\displaystyle\frac{40}{100}=15$$
$$x=37.5\;g$$
After heating mass of solution is $$=37.5\;g$$
Mass of water = Mass of solution - Mass of water
$$=37.5-15=22.5$$
Amount of water disappeared on heating
$$=(85-22.5)=62.5\;g$$
Question 7
1 / -0

One mole of any substance contains $$6.023\times10^{23}$$ particles. It was determined by

A
Berzilius

B
Avogadro

C
Dalton

D
Perin

Solution

Avogadro's law states that in one mole of any substance, a total number of $$6.023 \times 10^{23}$$ molecules are present.
So, option $$B$$ is correct.
Question 8
1 / -0

Which atom contains exactly 15 neutrons?

A
$$P^{32}$$ (atomic number $$= 17$$)

B
$$S^{32}$$ (atomic number $$= 16$$)

C
$$O^{15}$$ (atomic number $$= 8$$)

D
$$N^{15}$$ (atomic number $$= 7$$)

Solution

$$mass\space number= no. of \space protons + no. of\space neutrons$$
Given that mass number of P = 32
Atomic number (no. of electrons $$=$$ no. of protons) $$=$$ 17
Number of neutrons $$= 32 - 17 = 15$$
Hence, P satisfies the requirement.
Question 9
1 / -0

In a chemical reaction, when 14 g of sodium carbonate reacted with 10g of acetic acid (ethanoic acid), then it was observed that, 16.67 g of sodium acetate solution in water and 7.33 g of carbon dioxide were produced. Which law does this depicts?

A
Law of definite proportions

B
Law of conservation of mass

C
Law of constant proportions

D
Avogadro's law

Solution

In the given reaction,
$$\underset {(14g)}{\text {Sodium carbonate}}+\underset {(10g)}{\text {Ethanoic acid}}\Rightarrow \underset {(16.67)}{(Sodium ethanoate+water)}+\underset {(7.33 g)}{Carbon dioxide gas}$$
Total mass of all reactants combined
$$=14 g+10 g=24 g$$
Total mass of all the products formed
$$= 16.67 g + 7.33 g =24 g$$.
It is observed that Total mass of all reactants combined $$= 24 g =$$ Total mass of all the products formed. Therefore, the given observations are in agreement with the law of conservation of mass.
Question 10
1 / -0

How much MgO is obtained on heating 5 gm of $$\displaystyle \left ( MgCO_{3} \right )$$ Magnesium carbonate?

A
2.4 gm

B
2.38 gm

C
2.8 gm

D
3.28 gm

Solution

$$\displaystyle MgCO_{3}\rightarrow MgO+CO_{2}$$
Molecular weight of $$\displaystyle MgCO_{3}$$
= 24 + 12 +16 x 3 = 84
Molecular weight of MgO
= 24 + 16 = 40
On heating 84 gms of $$\displaystyle MgCO_{3}$$ the quantity of MgO obtained
= 40 gms
$$\displaystyle \therefore $$ On heating 5 gms of $$\displaystyle MgCO_{3}$$ the quantity of MgO obtained
$$\displaystyle = \frac{40}{84} X 5gms$$
= 2.38 gms

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Re-Attempt Weekly Quiz Competition

Some Basic Concepts of Chemistry Test - 29

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Some Basic Concepts of Chemistry Test - 29

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Question 1

26.07

2.607

260.7

None of these

Solution

Question 2

conservation of mass

multiple proportion

constant proportion

reciprocal proportion

Solution

Question 3

$$64\;g$$

$$0.64\;g$$

$$6.4\;g$$

$$4.6\;g$$

Solution

Question 4

64 g

0.64g

6.4g

4.6 g

Solution

Question 5

A, C, B

C, A, B

B, C, A

C, B, A

Solution

Question 6

$$0.0625\;g$$

$$62.5\;g$$

$$0.625\;g$$

$$6.25\;g$$

Solution

Question 7

Berzilius

Avogadro

Dalton

Perin

Solution

Question 8

$$P^{32}$$ (atomic number $$= 17$$)

$$S^{32}$$ (atomic number $$= 16$$)

$$O^{15}$$ (atomic number $$= 8$$)

$$N^{15}$$ (atomic number $$= 7$$)

Solution

Question 9

Law of definite proportions

Law of conservation of mass

Law of constant proportions

Avogadro's law

Solution

Question 10

2.4 gm

2.38 gm

2.8 gm

3.28 gm

Solution

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