Practice

Nature of Matter: Elements, Compounds, and Mixtures — Practice

15 questions 15 min Recall + understand

Q1. Two or more substances mixed together, where each substance retains its own properties, are together called a
- A. Compound
- B. Mixture
- C. Element
- D. Molecule
Q2. The individual substances that make up a mixture are called its
- A. Atoms
- B. Molecules
- C. Components
- D. Compounds
Q3. Mixtures in which the different components are generally visible with the naked eye or a magnifying device are described as
- A. Uniform
- B. Non-uniform
- C. Pure
- D. Compound
Q4. A mixture in which the components are evenly distributed and cannot be distinguished even with a microscope is called
- A. Non-uniform
- B. Heterogeneous suspension
- C. Uniform
- D. Compound
Q5. A pure substance that cannot be broken down further into simpler substances is called a/an
- A. Element
- B. Compound
- C. Mixture
- D. Alloy
Q6. Substances formed when different elements combine chemically in a fixed ratio to form something entirely new are called
- A. Mixtures
- B. Compounds
- C. Alloys
- D. Minerals
Q7. In Activity 8.1, lime water left in a petri dish turns milky after some time. This confirms the presence of which gas in the air?
- A. Oxygen
- B. Nitrogen
- C. Carbon dioxide
- D. Hydrogen
Q8. In Activity 8.3, when a burning candle is brought near one of the gas-filled test tubes, a 'pop' sound is heard. The gas in this test tube is
- A. Carbon dioxide
- B. Hydrogen
- C. Oxygen
- D. Water vapour
Q9. Stainless steel, brass and bronze are examples of
- A. Pure elements
- B. Alloys
- C. Compounds
- D. Native minerals
Q10. Each element is made up of identical particles called
- A. Molecules
- B. Compounds
- C. Atoms
- D. Crystals
Q11. According to the chapter, the total number of elements known at present is
- A. 92
- B. 108
- C. 118
- D. 128
Q12. In water, the ratio of the number of atoms of hydrogen to oxygen is
- A. 1 : 1
- B. 1 : 2
- C. 2 : 1
- D. 2 : 3
Q13. Which gas constitutes about 78% of the air but does not take part in combustion?
- A. Oxygen
- B. Carbon dioxide
- C. Argon
- D. Nitrogen
Q14. In Activity 8.5, the black mass formed by heating the mixture of iron filings and sulfur powder is
- A. Iron oxide
- B. Iron sulfide
- C. Iron chloride
- D. Hydrogen sulfide
Q15. When a scientist says a substance is pure, it means the substance
- A. Has not been adulterated with cheaper material
- B. Consists of the same type of particles
- C. Comes from a trusted brand
- D. Is the costliest variety available

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