Answer:
option a
Explanation:
The group number of an element is equal to the number of electrons the outermost shell (or highest energy level) contains
Energy can make matter do all of the above, so D
I think the answer is 10g
when you freeze a specific amount of water into an ice cube, only the form and the density is changed, while the mass will be pretty much the same.
Probably the mass of the melted water will be a little bit less than the cube (if count the mass that released to the air) , but the amount will NOT BE SIGNIFICANT.
Answer:
A)A compound that donates protons
Explanation:
for B it is the defination of bases
Answer:
Ka = ( About ) 5 x 10^ - 8
Explanation:
Let us first identify the dissociation equation for this weak acid,
HA ⇌ ( H+ ) + A¯
Knowing this, we can tell what the equilibrium expression is, respectively,
Ka = ( [ H+ ] [ A¯ ] ) / [ HA ]
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Now let us use the given pH 3.99 to calculate [ H+ ], knowing that pH = −log [H+],
3.99 = - log[H+],
[H+] = 10 ^ - 3.99,
[H+] = ( About ) 1 * 10^-4 M
Substitute known values into the equilibrium expression,
Ka = [( 1 x 10^ - 4 ) ( 1 x 10^ ¯4 )] / 0.199,
Ka = ( About ) 5 x 10^ - 8
