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geniusboy [140]
2 years ago
8

A radioactive substance has a half-life of 5 million years. What is the age of a rock in which 25% of the original radioactive a

toms remain? You must show your work or explain how you came up with your answer for full credit.
Chemistry
1 answer:
GenaCL600 [577]2 years ago
5 0

Answer:

10 million years

Explanation:

For a sample to decay to 25% of its original amount, 2 half lives must have passed. Since one half life is 5 million years, multiplying this by 2 gives us that 2 half lives is 10 million years.

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Determine the pH of a 0.048 M hypochlorous acid (HClO) solution. Hypochlorous acid is a weak acid (Ka = 4.0 ✕ 10−8 M).
storchak [24]

pH of 0.048 M HClO is 4.35.

<u>Explanation:</u>

HClO is a weak acid and it is dissociated as,

HClO ⇄ H⁺ + ClO⁻

We can write the equilibrium expression as,

Ka = $\frac{[H^{+}] [ClO^{-}]  }{[HClO]}

Ka = 4.0 × 10⁻⁸ M

4.0 × 10⁻⁸ M = $\frac{x \times x }{0.048}

Now we can find x by rewriting the equation as,

x² =  4.0 × 10⁻⁸ × 0.048

   = 1.92 × 10⁻⁹

Taking sqrt on both sides, we will get,

x = [H⁺] = 4.38 × 10⁻⁵

pH = -log₁₀[H⁺]

     = - log₁₀[ 4.38 × 10⁻⁵]

   = 4.35

8 0
2 years ago
How is wavelength measured (Select all that apply. from the trough (bottom) of one wave to the trough of the next wave
mr Goodwill [35]

Answer:

The first two

5 0
2 years ago
Read 2 more answers
Use the information below to explain why the atomic radius decreases down a group.
notsponge [240]

Answer:

Detail is given below

Explanation:

Atomic radii trend along group:

As we move down the group atomic radii increased with increase of atomic number. The addition of electron in next level cause the atomic radii to increased. The hold of nucleus on valance shell become weaker because of shielding of electrons thus size of atom increased.

As the size of atom increases the ionization energy from top to bottom also  decreases because it becomes easier to remove the electron because of less nuclear attraction and as more electrons are added the outer electrons becomes more shielded and away from nucleus.

In A we can see that there is one positive charge and force of attraction is 2.30×10⁻⁸ N and distance is 0.10 nm

In B we can see that negative charge is further away from nucleus because of greater distance thus force of attraction will be less. 0.58×10⁻⁸ N

In C this distance further increases and force also goes in decreasing 0.26×10⁻⁸ N.

3 0
3 years ago
HELP!!!!!!!!!!! *What are some of the safety concerns for Barium sulfate &amp; Barium Sulfide? Explain
Alex

BaSO₄ is relatively harmless, but BaS is highly toxic.

BaSO₄ is quite insoluble (240 µg/100 mL). It is a <em>mild irritant</em> in cases of skin contact and inhalation. However, it is <em>safe enough</em> that health professionals ask patients to drink a suspension of BaSO₄. The Ba is opaque to X-rays, so it makes the stomach and intestines more visible to radiographers.

BaS is soluble (7.7 g/100 mL). It reacts slowly with water and more rapidly in the acid conditions of the stomach to <em>release H₂S</em>.

BaS + 2HCl ⟶ BaCl₂ + H₂S

An H₂S concentration of 60 mg/100 mL can be <em>fatal within 30 min</em>.

<em>Don’t eat barium sulfide!</em>

3 0
3 years ago
Standard temperature and pressure (STP), in the context of gases, refers to a) 298.15 K and 1 atm b) 273.15 K and 1 atm c) 298.1
lina2011 [118]

Answer : The correct option is, (B) 273.15 K and 1 atm

Explanation :

STP : STP stands for standard temperature and pressure.

STP conditions :

The temperature is, 0^oC or 273.15K or 32^oF

The pressure is, 1atm or 101.325kPa

The volume is 22.4 L for 1 mole of a substance.

Hence, the correct option is, (B) 273.15 K and 1 atm

7 0
2 years ago
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