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SVETLANKA909090 [29]
3 years ago
15

Can anyone help me with this asap?

Chemistry
1 answer:
tresset_1 [31]3 years ago
3 0

Answer:

Explanation:

1) During the diagnosis of thyroid disease a 10 g sample of I-131 is used. After a period of 32 days, how much sample is still radio active.?

Answer:

0.625 g

Explanation:

HL = Elapsed time/half life

32 days/8 days = 4

At time zero = 10 g

At 1st half life = 10/2 = 5 g

At 2nd half life = 5/2 = 2.5 g

At 3rd half life = 2.5 /2 = 1.25 g

At 4th half life = 1.25 / 2 = 0.625 g

After 32 days still 0.625 g of I-131 remain radioactive.

2) what was the original mass of sample Tc-99 that was used to locate the brain tumor If 0.10 g of a sample remains after 30 days? (half life 6 days)

Answer:

0.32 g.

Explanation:

Half life = time elapsed / HL

Half life = 30 days / 6 days = 5

At 5th half life = 0.10 g

At 4th half life = 0.2 g

At 3rd half life =  0.4 g

At 2nd  half life = 0.8 g

At 1st half life = 0.16 g

At time zero = 0.32 g

The original amount was 0.32 g.

3) write the beta decay equation of I-131?

Equation:

¹³¹I₅₃  →  ¹³¹Xe₅₄ + ⁰₋₁e

Beta radiations are result from the beta decay in which electron is ejected. The neutron inside of the nucleus converted into the proton an thus emit the electron which is called β particle.

The mass of beta particle is smaller than the alpha particles.

They can travel in air in few meter distance.

These radiations can penetrate into the human skin.

The sheet of aluminium is used to block the beta radiation

¹³¹I₅₃  →  ¹³¹Xe₅₄ + ⁰₋₁e

The beta radiations are emitted in this reaction. The one electron is ejected and neutron is converted into proton.

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True or false : Color Changes are used to show reaction completion
Aleks [24]

Answer:

True

Explanation:

It means the reaction is occuring.

7 0
3 years ago
What atomic or hybrid orbital on sb makes up the sigma bond between sb and f in antimony(iii) fluoride, sbf3?
Afina-wow [57]

Answer: The four sp^3 hybridized orbitals on Sb makes up the sigma bonds between Sb and F in antimony(iii) fluoride ,SbF_3

Explanation:

According to VESPR theory:

Number of electrons around the central atom : \frac{1}{2}[V+N-C+A]

V = number of valence electrons

N = number of neighboring atoms

C = charge on cation

A = charge on an anion

In antimony(III) fluoride ,

Antimony being central atom: V= 5,N =3,C=0,A=0

Number of electrons : \frac{1}{2}[V+N-C+A]=4

Number of electrons around the central atom are 4 which means that SbF_3 molecule has four sp^3 hybridized orbitals.

6 0
3 years ago
A gas of unknown molecular mass was allowed to effuse through a small opening under constant-pressure conditions. It required 10
masya89 [10]

<u>Answer:</u> The molar mass of unknown gas is 367.12 g/mol

<u>Explanation:</u>

Rate of a gas is defined as the amount of gas displaced in a given amount of time.

\text{Rate}=\frac{V}{t}

To calculate the rate of diffusion of gas, we use Graham's Law.

This law states that the rate of effusion or diffusion of gas is inversely proportional to the square root of the molar mass of the gas. The equation given by this law follows the equation:

\text{Rate of effusion}\propto \frac{1}{\sqrt{\text{Molar mass of the gas}}}

So,

\left(\frac{\frac{V_{X}}{t_{X}}}{\frac{V_{O_2}}{t_{O_2}}}\right)=\sqrt{\frac{M_{O_2}}{M_{X}}}

We are given:

Volume of unknown gas (X) = 1.0 L

Volume of oxygen gas = 1.0 L

Time taken by unknown gas (X) = 105 seconds

Time taken by oxygen gas = 31 seconds

Molar mass of oxygen gas = 32 g/mol

Molar mass of unknown gas (X) = ? g/mol

Putting values in above equation, we get:

\left(\frac{\frac{1.0}{105}}{\frac{1.0}{31}}\right)=\sqrt{\frac{32}{M_X}}\\\\M_X=367.12g/mol

Hence, the molar mass of unknown gas is 367.12 g/mol

3 0
4 years ago
Based on Chromium's position on the periodic table, which statement describes the element
mash [69]

Answer:

C. chromium is a metal that is less reactive than sodium.

Explanation:

Hello.

In this case, since chromium is in period 4 group VIB we infer it is a transition metal which slightly reacts with acids and poorly reacts with oxygen and other oxidizing substances. Thus, in comparison with both sodium and potassium which are highly reactive even with water as they get on fire, we can say that it is less reactive than both potassium and sodium, therefore, answer is: C. chromium is a metal that is less reactive than sodium.

Best regards.

5 0
3 years ago
An aqueous solution of glycerol, c3h8o3, is 48.0% glycerol by mass and has a density of 1.120 g ml-1. calculate the molality of
garik1379 [7]
Answer is: <span>the molality of the glycerol solution is 10.03 m.
V(solution) = 100 mL.
m</span>(solution) = V(solution) · d(solution).
m(solution) = 100 mL ·1.120 g/mL.
m(solution) = 112 g.
m(glycerol) = ω(glycerol) · m(solution).
m(glycerol) = 0.48 · 112 g.
m(glycerol) = 53.76 g.
m(water) = 112 g - 53.76 g.
m(water) = 58.24 g ÷ 1000 g/kg = 0.05824 kg.
n(C₃H₈O₃) = m(C₃H₈O₃) ÷ M(C₃H₈O₃).
n(C₃H₈O₃) = 53.76 g ÷ 92 g/mol.
n(C₃H₈O₃) = 0.584 mol.
b(C₃H₈O₃) = n(C₃H₈O₃) ÷ m(H₂O).
b(C₃H₈O₃) = 0.584 mol ÷ 0.05824 kg.
m(C₃H₈O₃) = 10.027 mol/kg.

4 0
3 years ago
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