Answer:
d. T1 = 7°C; T2 = 29°C
Explanation:
The temperature of a substance is a measure of the average kinetic energy of is particle: in fact, the two quantities are proportional to each other.
Moreover, heat is always transferred spontaneously from a hotter object (higher temperature) to a colder object (lower temperature).
In this problem, we have a container placed in contact with a bucket of hot water: heat flows from the hot water to the container, until the two are at the same temperature.
The amount of energy transferred between the two is proportional to the initial temperature difference between the container and the water:

Since in the two situations the amount of energy transferred is the same, then it means that the temperature difference between the two substances is the same in the two situations. So we can write:

And from the choices given, we see that the only option that satisfies this condition is

From the combustion of octane, the formaldehyde will be formed as this equation:
C8H18 + O2 → CH2O + H2O this is the original equation but it is not a balanced equation, so let's start to balance it:
the equation to be balanced so the number of atoms on the right side of the equation sholud be equal with the number of atoms on the lef side.
-we have 8 C atoms on left side and 1 atom on the right side so we will try putting 8 CH2O on the right side instead of CH2O
C8H18 + O2 → 8 CH2O + H2O
we have 2 O atoms on the left side and 9 atoms on the right side so we will try first to put 9 O2 instead of O2 on the left side and put 2H2O on the right side and put 16 CH2O instead of 8 CH2O to make the atoms of O are equal on both sides = 18 atoms
C8H18 + 9 O2 → 16 CH2O + 2H2O
put now we have 8 atom C on the left side and 16 atom on the right side so, we will put 2 C8H18 instead of C8H18 now we get this equation:
2C8H18 + 9O2 →16 CH2O + 2H2O
-now we have 36 of H atoms on both sides.
- and 16 of C atoms on both sides.
- and 18 of O atoms on both sides.
now all the number of atoms of O & C & H are equal on both sides
∴ 2C8H18 + 9O2 → 16 CH2O + 2 H2O
is the final balanced equation for the formation of formaldehayde
Answer:
CO32−
Explanation:
We have to consider the valencies of the polyatomic ions involved. Recall that it is only a polyatomic ion with a valency of -2 that can form a compound which requires two sodium ions.
When we look closely at the options, we will realize that among all the options, only CO32− has a valency of -2, hence it must be the required answer. In order to be double sure, we put down the ionic reaction equation as follows;
2Na^+(aq) + CO3^2-(aq) ---------> Na2CO3(aq)
There are FOUR electrons in the 3p sub-level of sulfur....