Shipa was preparing milk for her younger brother. She used a steel spoon to stir sugar into the boiling milk. She heard the doorbell ring while preparing the milk, so she turned off the gas burner, left the spoon in the container, and went to open the door. When she returned to the kitchen after five minutes and touched the spoon, it was hot.

Based on your understanding, answer the following questions:

1. What material is used to make the spoon?

2. Why did the spoon become hot despite the fact that it had not been heated?

Prasanna and Raksha brought a small puppy. He is very clever and enjoys playing with them at all times. After a few days, they noticed their puppy growing. So they decided to build a kennel for their dog. They are discussing the material that will be used to build the kennel. They listed some of the properties that the material should have. Guess the properties that Prasanna and Raksha thought of.

Based on your understanding, which of the following materials do you believe is appropriate for these requirements? Give reasons for your choice.
(a) Plastic (b) Metal (c) Glass (d) Wood (e) Ceramic (f) Cement (g) rubber (h) Paper

Prasanna performed magic in front of his friends. He placed a beaker filled with water on a table and asked his friends to drop an egg into it. All of his friends did the same thing, but each time the egg sank into the water. Then, Prasanna secretly mixed some white powder into the water and placed an egg in the beaker. Surprisingly, the egg began to float in water.

Answer the following questions based on the above comprehension.

a. What could be the white powder?

b. Why did the egg sink earlier but float later?

Navika’s teacher asked all the students to bring lemon, sugar and water for Nimbu paani making activity in the class. Navika added sugar and salt to water and stirred it with a spoon. She saw that sugar and salt got disappeared in water. Then she added lemon juice which also gets mixed well in the water to make delicious nimbu paani.

Based on the information answer the following questions:

a. Why did sugar and salt disappear in water?

b. Why do you think we drink nimbu paani in summer?

c. Name two other substances that do not dissolve in water.

It was Rama's birthday. Her friends and relatives all gathered to celebrate her birthday. Her grandmother gave her two gifts made of metal, one old dull silver spoon and a pair of lustrous gold earrings.

She was surprised to see the difference in the appearance of the two metals. Can you explain the reason for this difference?

Vivek and Rahul are childhood friends. They both started kiryana shops in their village. They brought similar articles from wholesale vendors in the city and sold them at fixed prices from their shops. Vivek used to have good sales, however, the customers were not happy with Rahul. Many a times he could not locate the articles and the customers need to wait for a long periods of time.

Suggest ways to improve the retail sale of Rahul? 

Riya went to a restaurant for dinner with her family. In the restaurant she saw beautiful electric switches and she asked her father whether these switches are made up of metals? The electric board and switches fitted at Riya's home looks different from what she saw at the restaurant. 

Riya's father explained to her that all the electric switches/boards are made up of plastic or wood. Why are the electric boards fitted on the wall made of plastic or wood?

Ten-year-old Janavi lives with her parents and two siblings. She is the eldest child of her parents. Last month, her younger brother, who is barely 6 years old, fell ill due to diarrhoea.

Her mother took him to the village dispensary where the doctor handed her few packets of ORS. He advised her to mix the contents in water(1 litre per pack) and give the solution to her brother at regular intervals. This saved the little boy's life.

a) What is the composition of ORS?
(b) Is the ORS solution homogeneous or heterogeneous?

Seema heard a news that due to increase in temperature of water bodies fish are dying. Water in the rivers and ponds contains a proper amount of dissolved gases which provide sufficient oxygen for the aquatic animals to respire.

What do you think, the increased temperature has changed in water bodies?