Heat and Changes (Class 7)

What this worksheet covers

This is an eighteen-question practice worksheet on heat, physical and chemical changes for Class 7, written to the pattern of the SOF National Science Olympiad (NSO). It carries 24 marks and is designed to be attempted in 45 minutes, split across three sections — Scientific Reasoning, Applying What You Know and Achievers Section. Every question is multiple choice with exactly one correct option, and every one comes with a fully worked solution rather than just an answer key — so a child who gets one wrong can see where the reasoning went astray instead of only learning that it did.

Skills your child practises

• Applied problem-solving on heat, physical and chemical changes at Class 7 level
• Working accurately against a time limit, as the real paper demands
• Scientific Reasoning questions in the olympiad format
• Applying What You Know questions in the olympiad format
• Achievers Section questions in the olympiad format
• Reading worked solutions to find the step that went wrong

How to use it

1. 1There are 18 questions in this worksheet. All questions are compulsory.
2. 2Each question has four options (A), (B), (C) and (D). Exactly one option is correct.
3. 3Questions 1–15 carry 1 mark each. Questions 16–18 (Achievers Section) carry 3 marks each.
4. 4There is no negative marking. Study every diagram and table carefully.

Sample questions from this worksheet

A preview of what's inside Heat and Changes (Class 7) — the PDF has the full set, and every question comes with a worked solution like these.

1. 1. The transfer of heat through a solid, without the solid itself moving, is called _______.

   • AConductioncorrect
   • BConvection
   • CRadiation
   • DReflection
   Solution: In conduction, heat passes from particle to particle through a solid. Convection needs the material itself to move, and radiation needs no medium at all.

2. 2. Why are cooking pans given wooden or plastic handles?

   • AThey look attractive
   • BThey conduct heat quickly away
   • CThey are lighter than metal
   • DWood and plastic are poor conductors, so the handle stays cool enough to holdcorrect
   Solution: Wood and plastic are poor conductors of heat, so very little heat travels along the handle and it stays cool enough to grip safely.

3. 3. Consider the following statements.(i) In a physical change no new substance is formed.(ii) All changes that give out heat are chemical changes.(iii) A chemical change is usually difficult to reverse.Which of the statements is/are correct?

   • A(i) and (ii) only
   • B(ii) and (iii) only
   • C(i) and (iii) onlycorrect
   • DAll three
   Solution: Statement (i) is true by definition. Statement (ii) is false — water freezing gives out heat but forms no new substance, so it is physical. Statement (iii) is true. Hence (i) and (iii).