The Mr is the mass numbers of each element added up so…. Fe = 56, O=16, H=1 … now add these up with the number of each element -> there’s 1 Fe, and 3 Os and 3 Hs as they are in brackets with a 3 outside-> (56+16+16+16+1+1+1=107) … your answer is 107
Answer is: there is 2,69·10²³ atoms of bromine.
m(CH₂Br₂) = 39,0 g.
n(CH₂Br₂) = m(CH₂Br₂) ÷ M(CH₂Br₂).
n(CH₂Br₂) = 39 g ÷ 173,83 g/mol.
n(CH₂Br₂) = 0,224 mol.
In one molecule of CH₂Br₂, there is two bromine atoms, so:
n(CH₂Br₂) : n(Br) = 1 : 2.
n(Br) = 0,448 mol.
N(Br) = n(Br) · Na.
N(Br) = 0,448 mol · 6,022·10²³ 1/mol.
n(Br) = 2,69·10²³.
Silicon has 14 protons Potassium has 19 electrons The neutrons are equal to the mass number minus the atomic number. Or the big number minus the small number on the periodic table. hydrogen 1 does not have a neutron.
iron =56 -26 for 30 neutrons in the nucleus
Chlorine 17 protons and 17 electrons. 18 or 19 neutrons on average.
Answer:
11.3 g
Explanation:
7.895 + 3.4 = 11.295
When rounded to correct number of significant figures --> 11.3
There are 3 significant figures in 11.3
