Answer:
Reverse the
reaction
Explanation:
Reactions:

Overall:

As can be seen, in the overall reaction we have
in the reactants like in the second reaction and
in the products. The
is in the first reaction but as a reactant so we need to reverse that reaction:

Combining:


Answer:
- <em><u>Option A. </u></em><u><em>2KClO₃ → 2KCl + 3O₂</em></u>
Explanation:
There are five basic general types of chemical reactions:
- Synthesis or combination reaction
- Single replacement reactions
- Double replacement reactions
The given reactions are:
- <u>2KClO₃ → 2KCl + 3O₂</u>
Which is, indeed, a decomposition reaction because the reactant, KClO₃, is a single substance that undergoes a reaction in which it yields two new substances, known as products: KCl and O₂.
- <u>4Na + O₂ → 2Na₂O</u> is a synthesis or combination reaction because two reactants, Na and O₂, combine for the formation of one single new product, Na₂O.
- <u>ZnS + 3 O₂ → 2ZnO + 2SO₂ </u>is a single replacement reaction because oxygen is replacing Zn and S in ZnS to form ZnO and plus SO₂.
- <u>2NaBr + CaF₂ → 2NaF + CaBr₂ </u>is a double replacement reaction because two ions (Br⁻ from NaBr and F⁻ from CaF₂) are exchanging places with other two ions (Na⁺ from NaBr and Ca²⁺ from CaF₂) two form two new ionic compounds (NaF and CaBr₂).
Answer:

Explanation:
A pressure of 1 atm and a temperature of 0 °C is the old definition of STP. Under these conditions, 1 mol of a gas occupies 22.4 L.
1. Calculate the moles of hydrogen.

2. Calculate the number of molecules

In all atoms, the number of protons and the number of electrons is always the same. The number of neutrons is very roughly the same as the number of protons, but sometimes it's rather more. The number of protons in an atom is called the atomic number and it tells you what type of atom you have.
<h3>
Answer:</h3>
= 5.79 × 10^19 molecules
<h3>
Explanation:</h3>
The molar mass of the compound is 312 g/mol
Mass of the compound is 30.0 mg equivalent to 0.030 g (1 g = 1000 mg)
We are required to calculate the number of molecules present
We will use the following steps;
<h3>Step 1: Calculate the number of moles of the compound </h3>

Therefore;
Moles of the compound will be;

= 9.615 × 10⁻5 mole
<h3>Step 2: Calculate the number of molecules present </h3>
Using the Avogadro's constant, 6.022 × 10^23
1 mole of a compound contains 6.022 × 10^23 molecules
Therefore;
9.615 × 10⁻5 moles of the compound will have ;
= 9.615 × 10⁻5 moles × 6.022 × 10^23 molecules
= 5.79 × 10^19 molecules
Therefore the compound contains 5.79 × 10^19 molecules