Which of the following are considered pure substances?
2 answers:
Answer: Option (A) is the correct answer.
Explanation:
A pure substance is defined a substance that contains atoms of same element and it has constant composition throughout the sample.
For example, sulfur, , nitrogen etc are all pure substances.
Whereas a compound is a substance that contains two or more substances which are combined together in a fixed composition.
For example, NaCl is a compound.
When components of solute are uniformly distributed in a solvent then the solution is known as homogeneous solution.
When components of solute are non-uniformly distributed in a solvent then the solution is known as heterogeneous solution.
Thus, we can conclude that elements are considered pure substances.
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Answer:
6. 7870 kg/m³ (3 s.f.)
7. 33.4 g (3 s.f.)
8. 12600 kg/m³ (3 s.f.)
Explanation:
6. The SI unit for density is kg/m³. Thus convert the mass to Kg and volume to m³ first.
1 kg= 1000g
1m³= 1 ×10⁶ cm³
Mass of iron bar
= 64.2g
= 64.2 ÷1000 kg
= 0.0642 kg
Volume of iron bar
= 8.16 cm³
= 8.16 ÷ 10⁶
Density of iron bar
= 7870 kg/m³ (3 s.f.)
7.
Mass
= 1.16 ×28.8
= 33.408 g
= 33.4 g (3 s.f.)
8. Volume of brick
= 12 cm³
Mass of brick
= 151 g
= 151 ÷ 1000 kg
= 0.151 kg
Density of brick
= mass ÷ volume
(3 s.f.)