Which of the following statements is true about a compound?

It has a fixed ratio of elements by mass

Burning of a candle is:

Both physical and chemical change

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Chemistry Holiday Homework

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Quiz containing chapter: -Elements,Compounds and Mixtures -Physical and Chemical Changes -Language of Chemistry

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Questions 15

Answers

1
Which is not a feature of a physical change?
Temporary
No new substance formed
Reversible
Energy is always absorbed
2
Which of the following solvents dissolve rust in them?
Benzene
Methylation sprit
Water
Oxalic acid
3
Which of these is a homogeneous mixture?
Sand and iron
Oil and water
Salt solution
Iron and sulphur
4
Valency of oxygen in water (H₂O) is:
2
3
4
1
5
Which is a correct balanced chemical equation?
2H₂ + O₂ → 2H₂O
2H₂ + 2O₂ → 2H₂O
H₂ + O₂ → H₂O
H₂ + O₂ → 2H₂O
6
Which of the following statements is true about a compound?
It can be separated by a magnet
Its components retain their original properties
It has a fixed ratio of elements by mass
It is always a liquid
7
Which pair correctly shows a molecule and its element?
CO₂ – Carbon
O₂ – Oxygen
HCl – Hydrogen
H₂O – Hydrogen
8
Which is the best method to separate ink from water?
Chromatography
Filtration
Decantation
Sedimentation
9
What type of change is reaction of vinegar and baking soda?
None
Physical
Chemical
Reversible
10
Which of the following indicates a chemical change ?
Change in size
Formation of a new substance
Melting
Change in shape
11
Which mixture is separated by sublimation?
Ammonium chloride and sand
Iron and sulphur
Salt and water
Sand and salt
12
Which of these is an irreversible physical change?
Melting wax
Melting ice cube
Breaking glass
Boiling water
13
How many atoms are in NaCl?
2
4
3
1
14
Burning of a candle is:
Only a chemical change
Both physical and chemical change
None of the above
Only a physical change
15
Which correctly represents 2 water molecules?
H₂O
2H₂O
H₂ + O₂
H₂O₂

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