A rock has 12.5 percent of its original amount of potassium-40 remaining in it; potassium-40 has a half-life of 1.25 billion years. How long ago was the rock formed?a) 1.25 billion years ago

b) 2.5 billion years ago

c) 3.75 billion years ago

d) 5 billion years ago

Answers

Answer 1

Answer: A rock has 12.5 percent of its original amount of potassium-40 remaining in it; potassium-40 has a half-life of 1.25 billion years. 3.75 billion years ago was the rock formed. the answer is letter C

Answer 2

Answer:

Answer:

the answer is b) 2.5 billion years. if its half life is 1.25 billion years and there is only 25% of the element remaining, you would take 1.25 billion and multiply it by two to get 2.5 billion.

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If salt is dissolved in water, water serves as the:a. solute.
b. solvent.
c. dissolved medium.
d. none of the above

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b. solvent

solute is the substance being dissolved

Which equations shows the complete dissociation of a strong base?

Answers

The correct answer is the fourth option. The complete dissociation of a strong base is BOH + h20 -> B+ + OH- + H20 since this is the only base from the choices given. A base is a substance that accepts hydrogen ions.

Ammonium hydroxide ionizes as follows: NH4OH(s) NH4 +(aq) + OH-(aq). If an excess of ammonium salt, such as NH4Cl (which ionizes to give NH4 +(aq) ions) is added to the equilibrium shown above, you could predict that the result will be to....

Answers

Answer: The dissociation of the base will be further suppressed.

Explanation: Any change in the equilibrium is studied on the basis of Le-Chatelier's principle.

This principle states that if there is any change in the variables of the reaction, the equilibrium will shift in the direction to minimize the effect.

For the given equation:

$NH_4OH(s)\rightleftharpoons NH_4^+(aq)+OH^-(aq)$

If an excess of ammonium salt, such as $NH_4Cl$ (which ionizes to give $NH_4^+$ (aq) ions)

$NH_4Cl\rightarrow NH_4^++Cl^-$

If the concentration of $NH_4^+$ that is the product is increased, so according to the Le-Chatelier's principle, the equilibrium will shift in the direction where decrease of concentration of $NH_4^+$ takes place. Therefore, the equilibrium will shift in the backward direction and the ions will start associating to form $NH_4OH$ .

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A chemistry teacher adds 50.0 mL of 1.50 M H2SO4 solution to 200 mL of water. What is the concentration of the final solution? A)0.300 M B)0.375 M. C)6.00 M. D)7.50 M.

Answers

this is a dilution equation where 50.0 mL of 1.50 M H₂SO₄ is taken and added to 200 mL of water.

c1v1 = c2v2

where c1 is concentration and v1 is volume of the concentrated solution

and c2 is concentration and v2 is volume of the diluted solution to be prepared

50.0 mL of 1.50 M H₂SO₄ is added to 200 mL of water so the final solution volume is - 200 + 50.0 = 250 mL

substituting these values in the formula

1.50 M x 50.0 mL = C x 250 mL

C = 0.300 M

concentration of the final solution is A) 0.300 M

Answer: 0.300M

Explanation:

1) Data:

a) Initial solution

M = 1.50M

V = 50.0 ml = 0.050 l

b) Solvent added = 200 ml = 0.200 l

2) Formula:

Molarity: M = moles of solute / volume of solution is liters

3) Solution:

a) initial solution:

Clearing moles from the molarity formula: moles = M × V

moles of H₂SO₄ = M × V = 1.5M × 0.050 l = 0.075 mol

b) final solution:

i) Volumen of solution = 0.050 l + 0.200l = 0.250l

ii) M = 0.075 mol / 0.250 l = 0.300M ← answeer

Using the following phase diagram, which line segment describes the interface between solid and vapor?A-B

B-C

A-B-C

B-D

Answers

In the given phase diagram, the line segment that describes the interface between solid and vapor is A-B. The rest of the choices do not answer teh question above

In Ernest Rutherford's gold foil experiments, some alpha particles were deflected from their original paths, but most passed through the foil with no deflection. Which statement about gold atoms is supported by these experimental observations?Gold atoms consist mostly of empty space.

Gold atoms are similar to alpha particles.

Alpha particles and gold nuclei have opposite charges.

Alpha particles are less dense than gold atoms.

Answers

According to ErnestRutherford's gold foil tests, the true statement is that space makes up the majority of gold atoms. The correct option is A.

According to Rutherford's studies, the majority of the alphaparticles encountered free space inside the atom since they mostly went through the gold foil with little to no deflection.

This finding helped scientists comprehend that atoms have a small, compact nucleus at their center and are primarily made up of empty space elsewhere in the atom.

The nuclearmodel of the atom was created as a result of the deflection of several alpha particles, which showed that they came into contact with the positively charged atom's nucleus.

Thus, the correct option is A.

For more details regarding Ernest Rutherford, visit:

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Your question seems incomplete, the probable complete question is:

A. Gold atoms consist mostly of empty space.

B. Gold atoms are similar to alpha particles.

C. Alpha particles and gold nuclei have opposite charges.

D. Alpha particles are less dense than gold atoms

Answer:

Explanation:

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