Question 1

Q1: Which separation techniques will you apply for the separation of the following? (a) Sodium chloride from its solution in water (b) Ammonium chloride f...

Accepted Answer

(a) Evaporation or Distillation (b) Sublimation (c) Filtration (d) Chromatography (e) Centrifugation (f) Separating funnel (g) Filtration (h) Magnetic separation (i) Winnowing (j) Filtration

Question 2

Q10: Classify the following into elements, compounds and mixtures. (a) Sodium (b) Soil (c) Sugar solution (d) Silver (e) Calcium carbonate (f) Tin (g) Sili...

Accepted Answer

Elements: (a) Sodium (d) Silver (f) Tin (g) Silicon Compounds: (e) Calcium carbonate (k) Methane (l) Carbon dioxide Mixtures: (b) Soil (c) Sugar solution (h) Coal (i) Air (j) Soap (m) Blood

Question 3

Q11: Which of the following are chemical changes? (a) Growth of a plant (b) Rusting of iron (c) Mixing of iron filings and sand (d) Cooking of food (e) Dig...

Accepted Answer

The following are chemical changes: (a) Growth of a plant (b) Rusting of iron (d) Cooking of food (e) Digestion of food (g) Burning of a candle

Question 4

Q2: Write the steps you would use for making tea. Use the words solution, solvent, solute, dissolve, soluble, insoluble, filtrate and residue.

Accepted Answer

1.  Take water (solvent) in a kettle and heat it. 2.  Add tea leaves (solute) to the hot water. The tea leaves are insoluble in water. 3.  The tea leaves release their color and flavor, forming a solution. 4.  Add sugar (solute) to the tea, which dissolves completely, forming a solution. 5.  Pour th...

Question 5

Q3: Pragya tested the solubility of three different substances at different temperatures and collected the data as given below (results are given in the f...

Accepted Answer

(a) At 313 K, 62 grams of potassium nitrate are needed to saturate 100 grams of water. Therefore, to saturate 50 grams of water, $\frac{62}{2} = 31$ grams of potassium nitrate would be needed. (b) As the solution cools, some of the potassium chloride will crystallize out of the solution. This is bec...

Question 6

Q4: Explain the following giving examples. (a) Saturated solution (b) Pure substance (c) Colloid (d) Suspension

Accepted Answer

(a) Saturated Solution: A saturated solution is one in which no more solute can be dissolved at a given temperature. If we add more solute, it will not dissolve and will settle at the bottom. For example, if you keep adding sugar to water at room temperature, a point will be reached when no more sug...

Question 7

Q5: Classify each of the following as a homogeneous or heterogeneous mixture. soda water, wood, air, soil, vinegar, filtered tea.

Accepted Answer

Homogeneous mixtures:    Soda water    Air    Vinegar    Filtered tea Heterogeneous mixtures:    Wood    Soil

Question 8

Q6: How would you confirm that a colourless liquid given to you is pure water?

Accepted Answer

To confirm that a colorless liquid is pure water, you can determine its boiling point. Pure water boils at 100°C (373 K) at standard atmospheric pressure. If the liquid boils exactly at this temperature, it is pure water. If it boils at a different temperature, it indicates the presence of impuritie...

Question 9

Q7: Which of the following materials fall in the category of a "pure substance"? (a) Ice (b) Milk (c) Iron (d) Hydrochloric acid (e) Calcium oxide (f) Mer...

Accepted Answer

The pure substances are: (a) Ice (c) Iron (d) Hydrochloric acid (e) Calcium oxide (f) Mercury

Question 10

Q8: Identify the solutions among the following mixtures. (a) Soil (b) Sea water (c) Air (d) Coal (e) Soda water

Accepted Answer

The solutions are: (b) Sea water (c) Air (e) Soda water

Question 11

Q9: Which of the following will show "Tyndall effect"? (a) Salt solution (b) Milk (c) Copper sulphate solution (d) Starch solution

Accepted Answer

The following will show the Tyndall effect: (b) Milk (d) Starch solution

NCERT Solutions