True.
SF are used for simplifying figures in a measurement to produce a more accurate reading.
Answer : The final temperature of the copper is, 
Solution :
Formula used :
where,
Q = heat gained = 299 cal
m = mass of copper = 52 g
c = specific heat of copper = 
= final temperature = ?
= initial temperature = 
Now put all the given values in the above formula, we get the final temperature of copper.
Therefore, the final temperature of the copper is,
Density=mass/ volume so you solve for volume and get 461.96 mL
16(2)/74.1=.431
.431x100= 43.1%
Following the law of conservation of mass, the mass percent of hydrogen in the resulting compound is 14.4%(wt/wt). This is assuming that all of the carbon reacts with all of the hydrogen. The solution is as follows:
mass % = mass hydrogen*100/total mass = 28.8*100/(28.8+171.2) = 14.4%
