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4 years ago

Which radioisotopes have the same decay mode and have half-lives greater than

Chemistry

2 answers:

Damm [24]4 years ago

5 0

The answer is (3) I-131 and P-32. They both have β- decay mode and with half-lives greater than hour. You can get these half-lives and decay mode from table N selected radioisotopes.

AveGali [126]4 years ago

4 0

The correct answer is (3)

I-131 and P-32

The explanation:

according to attached table:

- we can see that the half life of p 32 is 14.28d (more than one hour)

- and the half life of I-131 is 8.021 d (more than one hour)

and They both have β- decay mode and with half-lives greater than hour.

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Be sure to answer all parts. What is the [H3O+] and the pH of a buffer that consists of 0.26 M HNO2 and 0.89 M KNO2? (K, of HNO2

Aleksandr-060686 [28]

Answer : The $H_3O^+$ ion concentration is, $1.12\times 10^{-3}M$ and the pH of a buffer is, 2.95

Explanation : Given,

$K_a=7.1\times 10^{-4}$

Concentration of $HNO_2$ (weak acid)= 0.26 M

Concentration of $KNO_2$ (conjugate base or salt)= 0.89 M

First we have to calculate the value of $pK_a$ .

The expression used for the calculation of $pK_a$ is,

$pK_a=-\log (K_a)$

Now put the value of $K_a$ in this expression, we get:

$pK_a=-\log (7.1\times 10^{-4})$

$pK_a=4-\log (7.1)$

$pK_a=3.15$

Now we have to calculate the pH of the solution.

Using Henderson Hesselbach equation :

$pH=pK_a+\log \frac{[Salt]}{[Acid]}$

$pH=pK_a+\log \frac{[KNO_2]}{[HNO_2]}$

Now put all the given values in this expression, we get:

$pH=3.15+\log (\frac{0.89}{0.26})$

$pH=2.95$

The pH of a buffer is, 2.95

Now we have to calculate the $H_3O^+$ ion concentration.

$pH=-\log [H_3O^+]$

$2.95=-\log [H_3O^+]$

$[H_3O^+]=1.12\times 10^{-3}M$

The $H_3O^+$ ion concentration is, $1.12\times 10^{-3}M$

4 0

3 years ago

A gas is collected at 20.0 °C and 725.0 mm Hg. When the temperature is

krek1111 [17]

Answer:

676mmHg

Explanation:

Using the formula;

P1/T1 = P2/T2

Where;

P1 = initial pressure (mmHg)

P2 = final pressure (mmHg)

T1 = initial temperature (K)

T2 = final temperature (K)

According to the information provided in this question;

P1 = 725.0mmHg

P2 = ?

T1 = 20°C = 20 + 273 = 293K

T2 = 0°C = 0 + 273 = 273K

Using P1/T1 = P2/T2

725/293 = P2/273

Cross multiply

725 × 273 = 293 × P2

197925 = 293P2

P2 = 197925 ÷ 293

P2 = 676mmHg.

The resulting pressure is 676mmHg

3 0

3 years ago

When assigning electrons to orbitals, which would be the most likely 'address' for the next electron following the 5s2 electron?

Bess [88]

The answer is number 3, 4d1.

4 0

4 years ago

Read 2 more answers

In a gas the kinetic energy is?

Mice21 [21]

Answer:

The kinetic energy of the translational motion of an ideal gas depends on its temperature.

Explanation:

8 0

3 years ago

The absorbance of an equilibrium mixture containing FeSCN2 was measured at 447 nm and found to be 0.347. What is the equilibrium

Ksenya-84 [330]

Answer:

The concentration is $C = 1.11 mol/L$

Explanation:

From the question we are told that

The absorbance is $A = 0.347$

The length is $l = 447 nm = 447 *10^{-7} \ cm$

Generally absorbance is mathematically represented as

$A = \epsilon* C * l$

where $\epsilon$ is the molar absorptivity of FeSCN2 with a value $\epsilon = 7.0*10^3 L/cm/mol$

and $C$ is the equilibrium concentration of FeSCN2

$C = \frac{A}{\epsilon * l }$

substituting values

$C = \frac{0.347}{7.0*10^{3} * 447 *10^{-7} }$

$C = 1.11 mol/L$

5 0

3 years ago