Class 5 EVS Chapter 7 Question Answers - Chapter 7 - Experiments with Water

Q1. What makes an object float on water?
Ans: An object will float on water if:

• Its weight is less than the weight of the water it displaces.
• The water level rises enough to support the object.

This principle is known as buoyancy.

Q2. Why did the puri float in the hot oil?
Ans: The puri floated in the hot oil because:

• Its weight was less than the amount of oil it displaced.
• As it cooked, the puri puffed up, increasing its volume.
• This reduced density allowed it to float.

Q3. What happened to the eggs when Ayesha put too much salt in the water?
Ans: The eggs floated slightly when Ayesha added too much salt to the water. This occurred because:

• The water became denser due to the high salt concentration.
• The weight of the water displaced by the eggs was greater than the weight of the eggs themselves.

Q4. What are soluble substances?
Ans: Soluble substances are substances that disappear in water when we add them to it. Examples include salt, sugar, glucose, vinegar, and lemon juice.

Q5. What are insoluble substances?
Ans: Insoluble substances are substances that do not disappear in water but settle down when we add them to it. Examples include salt, sand, pebbles, chalk powder, and cement.

Q6. How can we dissolve things quickly in water?
Ans: To dissolve sugar quickly in water, Hamid can try the following methods:

• Stirring continuously while adding sugar to the water.
• Heating the water to increase its temperature.
• Using smaller sugar particles, such as powdered sugar, for faster dissolution.
• Adding more water to dilute the sugar effectively.

Q7. Why doesn't oil mix with water?
Ans: Oil does not mix with water because:

• It is an immiscible liquid.
• Oil forms a layer on the surface of the water.
• Oil and water have different densities.

Q8. What happens when we put drops of water, oil, and sugar solutions on the lid of a tiffin box and tilt it?
Ans: The behaviour of the drops on the lid of the tiffin box varies:

• Water drops slide down quickly.
• Oil and sugar solutions move slower.
• Oil and sugar solutions tend to stick to the lid, making them harder to slide.

Q9. What are soluble substances examples?
Ans: Salt, sugar, glucose, vinegar, and lemon juice are examples of soluble substances.

Q10. What are insoluble substances examples?
Ans: Salt, sand, pebbles, chalk powder, and cement are examples of insoluble substances.