There's two sig figs: the 1 and the zero. The 10^-2 contributes no sig figs.
Answer:
a. 0.60
b. 1.30
c. 4.00
d. 6.70
e. 10.20
Explanation:
The 3 attached files shows a comprehensive solution
to the problems with answers highlighted as above
Answer:
A precipitate forms; the colour changes.
Step-by-step explanation:
The formation of a precipitate a colour change are always signs that a chemical reaction has occurred.
A, B, C, and D are <em>wrong.</em> They are signs of a reaction, but you did not observe them here.
Answer:
True
Explanation:
Because fossil fuels are non-renewable resources and that means it take thousands of years to form. Also, it harm the environment and create this climate change. While renewable resources, however, don't take thousand of years to form and it do not harm the environment.
Answer:
A. DH° = –36 kJ
Explanation:
It is possible to obtain DH° of a reaction by the sum of DH° of half reactions. The DH° of the reaction:
B₂H₆(g) → 2B(s) + 3H₂(g)
Could be obtained from:
<em>(1) </em>2B(s) + 1.5O₂(g) → B₂O₃(s) DH° = –1273kJ
<em>(2) </em>B₂H₆(g) + 3O₂(g) → B₂O₃(s) + 3H₂O(g) DH° = –2035kJ
<em>(3) </em>H₂(g) + 0.5O₂(g) → H₂O(g) DH° = –242kJ
The sum of (2) - (1) gives:
B₂H₆(g) + 1.5O₂(g) → 2B(s) + 3H₂O(g) DH° = -2035kJ - (-1273kJ) = -762kJ
Now, this reaction - 3×(3):
B₂H₆(g) → 2B(s) + 3H₂(g) DH° = -762kJ - (3×-242kJ) = -36kJ
Thus, right answer is:
<em>A. DH° = –36 kJ</em>
