Answer:

Explanation:
Given that:
The Half-life of
=
is less than that of 
Although we are not given any value about the present weight of
.
So, consider the present weight in the percentage of
to be y%
Then, the time elapsed to get the present weight of
= 
Therefore;

here;
= Number of radioactive atoms relating to the weight of y of 
Thus:

--- (1)
However, Suppose the time elapsed from the initial stage to arrive at the weight of the percentage of
to be = 
Then:
---- (2)
here;
= Number of radioactive atoms of
relating to 3.0 a/o weight
Now, equating equation (1) and (2) together, we have:

replacing the half-life of
=
( since
)
∴

The time elapsed signifies how long the isotopic abundance of 235U equal to 3.0 a/o
Thus, The time elapsed is 
Answer:
Water uses adhesive forces that allow it to stick to certain surfaces such as glass.
Explanation:
When the angle between vertical direction and the glass wall is small, surface tension is stronger and the component of gravity perpendicular to the glass wall is small. The result of this causes water to stick to the side of a glass.
Hope this helps!
Answer:
A experimental investigation
Answer:
c. 2NH₃ + 2H₂O + Cu²⁺ → Cu(OH)₂(s) + 2NH₄⁺
Explanation:
A net ionic equation is a chemical equation that list only the species that are involved in the reaction.
The reaction of ammonia with copper(II) sulfate CuSO₄ in water is:
2NH₃ + 2H₂O + CuSO₄ → Cu(OH)₂(s) + 2NH₄⁺ + SO₄²⁻
In an ionic equation, salts are written as ions, that means CuSO₄ must be written as Cu²⁺ + SO₄²⁻. That is:
2NH₃ + 2H₂O + Cu²⁺ +<u> SO₄²⁻</u> → Cu(OH)₂(s) + 2NH₄⁺ + <u>SO₄²⁻</u>
As in a net ionic equation you must list only the species involved in the reaction (The underlined species don't react), the net ionic equation is:
<em>c</em>. <em>2NH₃ + 2H₂O + Cu²⁺ → Cu(OH)₂(s) + 2NH₄⁺</em>
<em></em>
I hope it helps!
Answer:- C. 16.4 L
Solution:- The given balanced equation is:

From this equation, there is 2:1 mol ratio between HCl and hydrogen gas. First of all we calculate the moles of hydrogen gas from given grams of HCl using stoichiometry and then the volume of hydrogen gas could be calculated using ideal gas law equation, PV = nRT.
Molar mass of HCl = 1.008 + 35.45 = 36.458 gram per mol
The calculations are shown below:

= 
Now we will use ideal gas equation to calculate the volume.
n = 0.672 mol
T = 25 + 273 = 298 K
P = 101.3 kPa = 1 atm
R = 
PV = nRT
1(V) = (0.672)(0.0821)(298)
V = 16.4 L
From calculations, 16.4 L of hydrogen gas are formed and so the correct choice is C.