200 mg in g:
200 mg / 1000 => 0.2 g
number of moles Al(OH)3 :
molar mass = 78.00 g/mol
1 mole ---------- 78.00 g
? moles -------- 0.2 g
0.2 x 1 / 78.00 => <span> 0.00256 moles of Al(OH)3
number of moles Mg(OH)2 :
molar mass = 58.32 g/mol
1 mole --------- 58.32 g
? moles ------- 0.2 g
0.2 x 1 / 58.32 => </span><span>0.00343 moles of Mg(OH)2
hope this helps!</span>
Answer:
that's because
Explanation:
as far as my knowledge is concerned
HCl(g) + H2O ⇄ H3O+ (aq) + Cl– (aq)
or, more simply (and truer to the original theory):
HCl(g) ⇄ H+ (aq) + Cl– (aq) or HCl(aq)
Significant figures are the digits that come after the first non-zero digit. The second value has 11 significant figures and is therefore the correct answer. However, the fourth answer has 4 significant figures and would also be a correct answer. So I don’t know if perhaps there has been a typo or a mistake in the question but with what you have provided here, both these answer have more than 2 significant figures.
<h3 /><h3>Further explanation</h3>
Given
Element K : 12 protons, 24 neutrons
Element L : 17 protons, 36 neutrons
Required
the number of protons, neutrons and electrons possessed by the ions of the two elements.
Solution
number of protons=atomic number = 12
electron configuration : 1s² 2s² 2p⁶ 3s²
The element will release 2 electrons to make it stable, thus forming a cation with a +2 charge
number of protons = 12
number of electrons = 10
number of neutrons = 24
number of protons=atomic number = 17
electron configuration : 1s² 2s² 2p⁶ 3s²3p⁵
The element will gain 1 electrons to make it stable, thus forming a anionwith a -1 charge
number of protons = 17
number of electrons = 18
number of neutrons = 36
<em>If we look at this problem, it looks like the numbers 24 and 36 are mass numbers, not the number of neutrons, so the possible elements are Mg and Cl, and the ions are Mg²⁺ and Cl⁻</em>