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Marina CMI [18]
2 years ago
9

David kept 100 grams of radioactive sodium in a container. He observed the amount of sodium left in the container after regular

intervals of time and recorded them in the table shown below.
Time (hours) Amount of sodium in container (in grams)
0 100
15 50
30 25
45 12.5

Based on the observations, which of these is most likely David's inference?
A.The half life period of radioactive sodium is 15 hours.
B.The half life period of radioactive sodium is 50 hours.
C.The amount of sodium left in the container after 60 hours will be 10.5 grams.
D.The amount of sodium left in the container after 60 hours will be 1.5 grams.
Chemistry
2 answers:
Anna [14]2 years ago
5 0
First we have to understand what a half life is. A half life is a measure of time when the amount of a certain object is 50% of the original amount. Hence the answer for this is letter A. The initial amount is 100. fifty percent of 100 is 50 and that happens after 15 hours. Hence, 15 hours is the half life period. 
Fudgin [204]2 years ago
5 0

Answer: A. The half life period of radioactive sodium is 15 hours.

Explanation:

Half life is the time taken by a reactant to reduce to its original concentration. It is designated by the symbol t_\frac{1}{2}.

Given:

At 0 hours the amount of sodium in container is 100 grams

After 15 hours , the amount of sodium in container is 50 grams which is half of the original amount of 100 grams.

It will take 15 hours for half of a 100 g sample to decay to half of the amount i.e. 50 grams.

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Write a balanced nuclear equation for the formation of 28 Si 14 from beta-minus emission.
Fantom [35]

Answer:

Phosphorus-28 undergoes beta-minus decay to produce

  • an electron,
  • a Silicon-28 nuclei, and
  • an electron antineutrino.

\rm ^{28}_{13} Al \to ^{28}_{14} Si + ^{\phantom{-}0}_{-1}e + \bar{\mathnormal{v}}_{\rm e}

Explanation:

In simple words, when a nucleus undergoes beta-minus decay, a neutron is converted to a proton. An electron and an electron antineutrino will be released.

\rm ^{1}_{0}n^{0} \to ^{1}_{1}p^{+} + ^{\phantom{-}0}_{-1}e^{-} + \bar{\mathnormal{v}}_{\rm e}.

One way to tell whether a neutron is converted to a proton, but not vice versa, is to check the sum charges on the two sides of this equation.

  • Left-hand side: 0. Neutron is neutral.
  • Right-hand side: 1 + (-1) = 0. Each proton carries a charge of +1. Each electron (beta-minus particle) carries a charge of -1. Antineutrinos are neutral.

The charges on the two sides of this equation is the same. Hence this nuclear equation is possible (but not necessarily correct; however, if the proton and the neutron are in the wrong place the charge won't even be the same.)

Since the mass number of a proton and a neutron are both 1, the overall mass number of the atom will stay the same.

The atomic number is the number of protons in each atom. That number determines the symbol and the chemical properties of the atom. When one neutron in an atom is converted to a proton, the atomic number of the atom will increase by 1.

The atomic number of the daughter nucleus, silicon, is 14. It takes a parent nucleus with atomic number 14 - 1 = 13 to produce a silicon atom. Refer to a modern periodic table. Atomic number 13 corresponds to the element aluminum.

Also, the mass number of the daughter nucleus is 28. Since the mass number would stay the same in a beta decay, the mass number of the parent nucleus would also be 28. In other words, it takes an aluminum-28 atom to undergo beta-decay to produce a silicon-28 atom.

Complete the other details (electron and electron antineutrino) to obtain the equation

\rm ^{28}_{13} Al \to ^{28}_{14} Si + ^{\phantom{-}0}_{-1}e + \bar{\mathnormal{v}}_{\rm e}.

6 0
3 years ago
If it take 20 second for 200cm3 of H25 to diffuse through a porovs pot,hours,long will it take 400cm3 of NH3 of diffuse under th
trapecia [35]

Answer:

40 seconds chief just double it

Explanation:

5 0
3 years ago
PLEASE ANSWER
lisov135 [29]

Answer:

B.

Explanation:

8 0
3 years ago
Convert mass to moles for both reactants. (round to 2 significant figures.)
Maslowich

Answer:

Explanation:

Given parameters:

Mass of CuCl₂  = 2.50g

Mass of Al  = 0.50g

Unknown:

Number of moles of CuCl₂ and Al  = ?

Solution:

To solve this problem, we must understand that the number of moles is a fundamental property used in stoichiometry calculations.

         Number of moles  = \frac{mass}{molar mass}

Molar mass of CuCl₂  = 63.6 + 2(35.5) = 134.5g/mole

Molar mass of Al  = 26.98g/mole

          Number of moles of  CuCl₂  = \frac{2.5}{134.5}  = 0.019moles

        Number of moles of Al  = \frac{0.5}{26.98}   = 0.019moles

4 0
3 years ago
Read 2 more answers
List the ions in solution in the electrolysis of conc.sodium chloride<br>​
Licemer1 [7]
Chloride ions Cl –(aq) (from the dissolved sodium chloride) are discharged at the positive electrode as chlorine gas, Cl 2(g) sodium ions Na +(aq) (from the dissolved sodium chloride) and hydroxide ions OH –(aq) (from the water) stay behind - they form sodium hydroxide solution, NaOH(aq)
5 0
2 years ago
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