Q1. Which of the following will show “Tyndall
effect”?
(a) salt solution (b)
milk (c) copper sulphate solution (d) starch solution.
Ans:
Both (b) and (d) are colloids hence display Tyndall Effect.
Q2. Classify the following into elements,
compounds and mixtures
(a) sodium (b) soil (c)
sugar solution (d) silver (e) calcium carbonate (f) tin
(g) silicon(h) coal
(i) air (j) soap (k) methane (l) carbon dioxide (m) blood
Ans:
Elements - sodium, silver, tin,
silicon.
Compounds - calcium carbonate, methane, carbon dioxide.
Mixtures -
soil, sugar solution, coal, air, soap, blood.
Q3. In the formation of sodium chloride from its
constituent elements, do the properties of its elements change. Explain.
Ans:
We observe that NaCl have entirely different properties than its constituent lements Na & Cl.Sodium is a highly
reactive metal that reacts vigorously with water( It catches fire that is why
kept in kerosin). It is highly dangerous to consume sodium. Likewise Chlorine
is a greenish yellow gas with a characteristic irritating odour. When these Na
& Cl combine to form sodium chloride, the properties of the elements are
totally changed. Sodium chloride is a white substance totally safe to be
ingested and is used to add taste to our food in daily use.
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