<span>when it comes to adding or subtracting numbers, his final answer should have the same number of decimal places as the least precise value.
For example if you add 2 numbers; 10.443 + 3.5 , 10.443 has 3 decimal places and 3.5 has only one decimal place.
Therefore 3.5 is the less precise value.
So when adding these 2 values the final answer should have only one decimal place.
after adding we get 13.943 but it can have upto one decimal place. then the second decimal place is less than 5 so the answer should be rounded off to 13.9.
the answer is the same number of decimal places as the least precise value</span>
Answer:- Mass of copper piece is 290 gram.
Solution:- We know that, mass = density * volume
density of copper is given as 8.96 gram per mL.
Volume of copper piece is the rise change in volume.
Volume of copper piece = 137 mL - 105 mL = 32 mL
Let's multiply the volume by density to calculate the mass of copper:
mass of copper = 
mass of copper = 286.72 g
Volume has two significant figures, so if we round the mass to two significant figures then it becomes 290 g.
Answer:
AC₄ will precipitate out first.
Explanation:
A solid will precipitate out if the ionic product of the solution exceeds the solubility product.
Let us check the ionic product
a) A₂B₃
Ionic product = [A]²[B]³
[A] = say "s"
[B] = 0.05 , [B]³ = (0.05)³ = 0.000125
2.3 X 10⁻⁸ = [A]²(0.000125)
[A] = 0.0136
b) AC₄
Ionic product = [A] [C]⁴
[A] = "s"
[A][0.05]⁴ = 4.10 X 10⁻⁸
[A]=0.00656 M
So for ionic product to exceed solubility product, we need less concentration of A in case of AC₄.
Answer: Thus the yield of uranium from 2.50 kg 
is 2.12 kg
Explanation:
According to avogadro's law, 1 mole of every substance weighs equal to molecular mass and contains avogadro's number 
of particles.
To calculate the number of moles, we use the equation:
moles of 
(1kg=1000g)
As 1 mole of contains = 3 moles of U
2.97 mole of contains = 
moles of U
Mass of Uranium=
( 1kg=1000g)
Thus the yield of uranium from 2.50 kg is 2.12 kg
Answer: the HCO3- to act as a base and remove excess H by the formation of H2CO3
Explanation:
H2CO3 in an aqueous solution is a buffer. This means the reaction is the following:
H2CO3 ------ HCO3- + H+
Then, the HCO3- that was formed acts as a base (absorbing a proton) like this
HCO3- + H+ ------- H2CO3
If there was an increase in H+, there would be an increase in the second reaction in an effort to neutralize that acid, thus making the H2CO3 more concentrated
