<h2><u>Answer</u> :</h2>
The most appropriate option is :

Since, they are the most abundant elements found in Earth's Crust.

Answer:
2.8g/cm³
Explanation:
Given parameters:
Mass of cube = 42g
Volume of cube = 15cm³
Unknown:
Density of the cube = ?
Solution:
Density is defined as the mass per unit volume of a substance. It is mathematically expressed as:
Density =
So;
Density =
= 2.8g/cm³
Answer:
The electrons that participate in chemical bonds are the valence electrons, which are the electrons found in an atom 's outermost shell.
Explanation:
Answer:
Option b. Decomposition
Followed by a reduction process using charcoal
Explanation:
Lead can be obtained from lead nitrate by thermal decomposition of lead nitrate as shown below:
2Pb(NO3)2 —> 2PbO + 4NO2 + O2
The PbO obtained is reduced by charcoal(C) to obtain the metallic Pb as shown below:
2PbO + C —> Pb + CO2
Answer:
K I will attempt
Explanation:
a)

b)
1 : 2 : 2 (I don't know if this is what the question wants but it is what I would answer)
c)
Hydrogen because it requires 2 moles of H2 to react with 1 mole of O2
d)
24 moles of water. Look at stoichiometric coefficient. 2:2 means 24 moles you get 24 moles
e)
Oxygen. 2 < 5/2. Remember, 1 mole of O2 requires 2 moles of H2. But 5/2 is still greater than 2
f)
First, let's find out how many moles of water we can get. Since O2 is the limiting reactant, and O2:H2O ratio is 1:2, we will get 4 moles of H2O. Then, we can multiply 4 by Avogadro's number which is
to get the number of molecules. We get: 2.41 * 10^24 molecules of water.