Explanation:
For multiplication or division, the rule is to count the number of significant figures in each number being multiplied or divided and then limit the significant figures in the answer to the lowest count.
a. 20.0 meters x 0012.65 meters
The numbers are;
20.0 (3 s.f) and 12.65 (4 s.f)
The multiplication gives; 253
Since 253 is already in 3 s.f, that's the answer.
b. 002.5 × 103 meters + 3.50 × 102 meters
The numbers are;
002.5 (2 s.f), 103 (3 s.f), 3.50 (3 s.f) and 102 (3 s.f)
002.5 × 103 = 257.5 = 260 (2 s.f)
3.50 × 102 = 357 = 360 (2 s.f)
260 + 360 = 620
Molar mass of methanol=12 + 1×3 + 16 + 1=32g
<span>
</span>
Answer : The correct option is, (D) 
Solution :
Formula used :
where,
Q = heat released = -1300 J
m = mass of water = 40 g
c = specific heat of water = 
= final temperature = ?
= initial temperature = 
Now put all the given values in the above formula, we get the final temperature of water.
Therefore, the final temperature of the water is,
The balanced chemical equation for the reaction is as below
KBr (aq) + AgNo3 → KNO3(aq) + AgBr(s)
Explanation
from the equation above the stoichiometric coefficient before KBr is 1, before AgNo3 is 1 , before KNO3 is 1 and before AgBr is also 1. Therefore 1 mole of KBr reacted with 1 mole of AgNO3 to form 1 mole of KNO3 and 1 mole of AgBr.
