1 / 343
This is just equal to
1 / 7^3 = 7^-3
A. 7^-1 * 7^-2 = 7^(-1 + -2) = 7^-3
B. 7^7 * 7^-10 = 7^( 7+ -10) = 7^-3
C. 7^-2 * 7^-5 = 7^(-2 + -5) = 7^-7
D. 7^-5 * 7^2 = 7^(-5 + 2) = 7^-3
So the correct answer is letter C. 7^-2 * 7^-5
Be more specific. The decimal can be anywhere give more detail
Ten cakes costs $2.19 (pounds, but I don't have a pounds symbol on my computer) because if you divide $2.10 by seven you get $0.3, and if you add 3×0.3 (because we have seven, and we need to add three more to get ten) we get $0.9.
0.9+2.10=2.19
ANSWER

and

EXPLANATION
Line s has equation:
y=x-5
And line t has equation:

We equate the two equations to get:

Multiply through by 4



7x=28


Given that I no not see any explanation in the previos answer, I think you can benefit of this.
Exothermic refers only to the fact that the reaction releases energy in the form of heat when occurs. So, the enthalpy is higher at start and lower and the end.
Seen in this way, you can deduct that the change in enthalpy is negative, which is what the third option says.