Answer : The time required for decay is, 84 days.
Explanation :
Half-life of chromium-51 = 28 days
First we have to calculate the rate constant, we use the formula :



Now we have to calculate the time required for decay.
Expression for rate law for first order kinetics is given by:

where,
k = rate constant
t = time taken by sample = ?
a = let initial activity of the sample = 100
a - x = amount left after decay process = 12.5
Now put all the given values in above equation, we get


Therefore, the time required for decay is, 84 days.
Answer:
The volume of the gas is 2.80 L.
Explanation:
An ideal gas is a theoretical gas that is considered to be made up of point particles that move randomly and do not interact with each other. Gases in general are ideal when they are at high temperatures and low pressures.
The Pressure (P) of a gas on the walls of the container that contains it, the Volume (V) it occupies, the Temperature (T) at which it is located and the amount of substance it contains (number of moles, n) are related from the equation known as Equation of State of Ideal Gases:
P*V = n*R*T
where R is the constant of ideal gases.
In this case:
- P= 2 atm
- V= ?
- n=0.223 moles
- R= 0.0821

- T=33 °C= 306 °K (being O°C= 273°K)
Replacing:
2 atm* V= 0.223 moles*0.0821
* 306 K
Solving:

V= 2.80 L
<u><em>The volume of the gas is 2.80 L.</em></u>
Answer:
9.8 × 10²⁴ molecules H₂O
General Formulas and Concepts:
<u>Atomic Structure</u>
- Reading a Periodic Table
- Moles
- Avogadro's Number - 6.022 × 10²³ atoms, molecules, formula units, etc.
<u>Organic</u>
<u>Stoichiometry</u>
- Analyzing reaction rxn
- Using Dimensional Analysis
Explanation:
<u>Step 1: Define</u>
[RxN - Unbalanced] CH₄ + O₂ → CO₂ + H₂O
[RxN - Balanced] CH₄ + 2O₂ → CO₂ + 2H₂O
[Given] 130 g CH₄
<u>Step 2: Identify Conversions</u>
Avogadro's Number
[RxN] 1 mol CH₄ → 2 mol H₂O
[PT] Molar Mass of C: 12.01 g/mol
[PT] Molar Mass of H: 1.01 g/mol
Molar Mass of CH₄: 12.01 + 4(1.01) = 16.05 g/mol
<u>Step 3: Stoichiometry</u>
- [DA] Set up conversion:

- [DA] Divide/Multiply [Cancel out units]:

<u>Step 4: Check</u>
<em>Follow sig fig rules and round. We are given 2 sig figs.</em>
9.75526 × 10²⁴ molecules H₂O ≈ 9.8 × 10²⁴ molecules H₂O
IT forms because they are highly reactive elements.
The color is an effect as a result of different wavelengths and frequencies of the light waves. So, color is a property of an object that depends on the wavelength. From all the given statements the following is true: T<span>he color depends upon the lighting source. More precisely, the color depends upon the wavelength of the lighting source.</span>