Atoms and Molecules Test

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Atoms and Molecules Test - 39

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Weekly Quiz Competition

Question 1
1 / -0

Compounds formed by metals and non-metals contain charged species which are known as:

A
cations

B
anions

C
Both A and C

D
None of the above

Solution

Compounds formed by metals and non-metals contain charged species which are known as ions. Such compounds are also known as ionic compounds. For example, $$NaCl$$ - it contains sodium ion (cation) and chloride ion (anion).
So, option C is correct.
Question 2
1 / -0

The illustrations show a conservation-of-mass experiment. The solution in the beaker lost mass because

A
materials have less mass at high temperatures

B
the mass of the reactants and products was less than $$100\ g$$

C
sodium sulfate $$(Na_{2}SO_{4})$$ is lighter than air

D
some of the water molecules turned into gas

Solution

The solution in the beaker lost mass as the solution contains water as it is aqueous so due to heat the water has been converted into gas.
The rest three options are not correct explanation.
Question 3
1 / -0

Formula unit mass of $$NaHCO_{3}$$ is :

A
$$84\ u$$

B
$$76\ u$$

C
$$52\ u$$

D
$$64\ u$$

Solution

Formula unit mass of $$NaHCO_{3} =$$ Mass of $$Na +$$ Mass of $$H+$$ Mass of $$C+$$ Mass of $$O$$
$$= 23\ u + 1\ u + 12\ u + 48\ u$$
$$= 84\ u$$
Question 4
1 / -0

The formula unit mass of $$X$$ is $$342\ u .$$ Among the following, X is :

A
$$H_2SO_4$$

B
$$PbI_2$$

C
$$Al_{2} (SO_{4})_{3}$$

D
$$Al(OH)_3$$

Solution

Formula unit mass of $$Al_{2}(SO_{4})_{3} = (2\times\ {Atomic \ mass\ of\ Al}) + (\text 3\times{Mass\ of\ S}) + (12\times\ {Mass\ of\ O}$$)
$$= 2\times 27\ u + 3\times 32\ u + 12\times 16\ u$$
$$=342\ u$$
Hence,option $$C$$ is correct.
Question 5
1 / -0

Formula unit mass of $$CaCO_{3}$$ is:

A
$$104\ u$$

B
$$106\ u$$

C
$$100\ u$$

D
$$1144\ u$$

Solution

Formula unit mass of $$CaCO_{3} = \text {Atomic mass of Ca} + \text {Atomic mass of C} + (\text {Atomic mass of O} \times 3)$$
$$= 40\ u + 12\ u + (16\ u\times3)$$
$$= 100\ u$$
Question 6
1 / -0

Which scientist proposed the concept of atomic mass?

A
Avogadro

B
Gay Lussac

C
Proust

D
Dalton

Solution

The concept of atomic mass was proposed by William Prout. Early atomic mass theory was proposed by the English chemist William Prout in a series of published papers in 1815 and 1816. Known as Prout's Law, Prout suggested that the known elements had atomic weights that were whole number multiples of the atomic mass of hydrogen.

Option C is correct.
Question 7
1 / -0

Sum of atomic masses of all atoms in a formula unit of an ionic compound is known as :

A
molecular mass

B
formula mass unit

C
atomic mass

D
none of the above

Solution

Formula unit mass is known as sum of atomic masses of all atoms in a formula unit of an ionic compound.
Question 8
1 / -0

Formula unit mass is calculated in the same way as molecular mass. There is a difference between them. What is it?

A
It is used for compounds whose constituent particles are not ions

B
It is used for substances whose constituent particles are ions

C
It is only used for substances with mass less than 100

D
None of the above

Solution

Formula mass unit is used to determine the mass of the formula of an ionic compound. Example:- $$NaCl$$
$$Na\longrightarrow 22.99 amu$$ [Atomic mass of sodium]
$$Cl\longrightarrow 35.34 amu$$ [Atomic mass of chlorine]
Total $$58.44 amu$$
This formula mass is the sum of the atomic masses of one sodium atom and one chlorine atom. $$58.44amu$$ is the formula mass of $$NaCl$$. Hence the correct answer is B.
Question 9
1 / -0

Molecular mass is expressed in:

A
kg

B
g

C
u

D
mg

Solution

Molecular mass is expressed in 'u', or unified atomic mass unit.
Question 10
1 / -0

What is the atomic mass (u) of chlorine?

A
34

B
35.5

C
33

D
35

Solution

Chlorine is a chemical element with the symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between them.

The atomic mass (u) of Chlorine is 35.5u.

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Re-Attempt Weekly Quiz Competition

Atoms and Molecules Test - 39

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Atoms and Molecules Test - 39

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SHARING IS CARING

Question 1

cations

anions

Both A and C

None of the above

Solution

Question 2

materials have less mass at high temperatures

the mass of the reactants and products was less than $$100\ g$$

sodium sulfate $$(Na_{2}SO_{4})$$ is lighter than air

some of the water molecules turned into gas

Solution

Question 3

$$84\ u$$

$$76\ u$$

$$52\ u$$

$$64\ u$$

Solution

Question 4

$$H_2SO_4$$

$$PbI_2$$

$$Al_{2} (SO_{4})_{3}$$

$$Al(OH)_3$$

Solution

Question 5

$$104\ u$$

$$106\ u$$

$$100\ u$$

$$1144\ u$$

Solution

Question 6

Avogadro

Gay Lussac

Proust

Dalton

Solution

Question 7

molecular mass

formula mass unit

atomic mass

none of the above

Solution

Question 8

It is used for compounds whose constituent particles are not ions

It is used for substances whose constituent particles are ions

It is only used for substances with mass less than 100

None of the above

Solution

Question 9

kg

g

u

mg

Solution

Question 10

34

35.5

33

35

Solution

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