Answer:
The parts of an atom are<em><u> protons, electrons, and neutrons.</u></em>
A proton is positively charged and is located in the center or nucleus of the atom.
Electrons are negatively charged and are located in rings or orbits spinning around the nucleus.
The number of protons and electrons is always equal.
Half-life is the time taken for the concentration of the substance to reduce by 50%. The original sample of strontium had a mass of 1.6 gms. Thus, option d is correct.
<h3>What is half-life?</h3>
The half-life of any radioactive substance is the time period at which the concentration will get reduced to half the initial amount. The initial mass of Sr-90 is calculated as,
Given,
Quantity of the remaining substance N (t) = 0.40 gm
Initial radioactive substance quantity 
=?
Time duration (t) = 56 years
Half-life = 28 years
Substituting values above:
= 1.6 gm
Therefore, option d. the initial mass of Sr is 1.6 gm.
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Answer:
not affected?
Explanation:
pretty sure M / concentration isn't affected, only volume.
The pH of the sodium hydroxide (NaOH) solution at the given concentration of 0.000519 M is determined as 10.72.
<h3>What is pH of solution?</h3>
The pH of a solution is defined as the logarithm of the reciprocal of the hydrogen ion concentration [H+] of the given solution.
Concentration of the basic solution, [OH⁻] = 0.000519
pOH = -log[OH⁻]
pOH = -log[0.000519]
pOH = 3.28
<h3>pH of the solution</h3>
pH + pOH = 14
pH = 14 - pOH
pH = 14 - 3.28
pH = 10.72
Thus, the pH of the sodium hydroxide (NaOH) solution at the given concentration of 0.000519 M is determined as 10.72.
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Answer:
The basic building blocks that make up matter are called atoms.
I hope it's helpful!
