NCERT Solutions for Class 6th Science Chapter 7 .3.2 Laboratory thermometer — Activity 7.4: Let us observe and calculate

Book page 1317 Updated on2026-09-19

Q1.

Note down the following: — How much is the temperature difference indicated between the two bigger marks?

Answer

On the thermometer of Fig. 7.3b, the bigger (numbered) marks are 0 °C, 10 °C, 20 °C, 30 °C and so on.

Difference between 0 °C and 10 °C = 10 °C – 0 °C = 10 °C
Difference between 10 °C and 20 °C = 20 °C – 10 °C = 10 °C

So the temperature difference indicated between two neighbouring bigger marks is 10 °C.

Q2.

How many divisions (shown by smaller marks) are there between these two bigger marks?

Answer

Count the small gaps, not the small lines. Between 0 °C and 10 °C on the thermometer of Fig. 7.3b there are 10 divisions.

A closeup of the scale, as in Fig. 7.3b. Between the two bigger marks 0 °C and 10 °C there are 10 small divisions, so one small division = 10 °C ÷ 10 = 1 °C.

Tip: Counting mistakes are common here. Count the spaces between marks, not the marks themselves — 10 spaces need 11 lines. Or count the small marks strictly between the two big ones and add 1; here 9 + 1 = 10.

Q3.

How much temperature does one small division indicate?

Answer

Divide the temperature difference by the number of divisions.

One small division = temperature between two big marks ÷ number of divisions
= 10 °C ÷ 10
= 1 °C

Q4.

So, the smallest value that the thermometer can read is _______ .

Answer

The smallest value that this thermometer can read is 1 °C.

What it means in practice: with this thermometer you can honestly write 26 °C or 27 °C, but you cannot write 26.5 °C — there is no mark there to read. The smallest value (also called the least count) fixes how precisely you are allowed to report a reading.

Q5.

Fig. 7.3b shows a closeup of a part of the thermometer shown in Fig. 7.3a. Can you now find the smallest value that this thermometer can read?

Fig. 7.3(b), page 131 — closeup of a part of the thermometer shown in Fig. 7.3(a). Count the small divisions between two numbered marks.

Answer

Yes — it is 1 °C. Here is the whole calculation in one place:

Temperature between 0 °C and 10 °C (or between 10 °C and 20 °C) = 10 °C
Number of divisions between those marks = 10
One small division = 10/10 = 1 °C
So the smallest value this thermometer can read = 1 °C

Your school laboratory may have thermometers for which the range and the smallest division are different. So always look carefully at the thermometer you are about to use before you take a reading.

Between two big marks	Number of divisions	Smallest value
10 °C	10	1 °C
10 °C	20	0.5 °C
10 °C	5	2 °C
5 °C	10	0.5 °C

Was this helpful?