All categories

3 years ago

PLEASE HELP this is physical science.

Chemistry

1 answer:

Andru [333]3 years ago

6 0

Bone age : 22,920 years

<h3>Further explanation</h3>

Given

Nt = 2.5 g C-14

No = 40 g

half-life = 5730 years

Required

time of decay

Solution

General formulas used in decay:

$\large{\boxed{\bold{N_t=N_0(\dfrac{1}{2})^{t/t\frac{1}{2} }}}$

t = duration of decay

t 1/2 = half-life

N₀ = the number of initial radioactive atoms

Nt = the number of radioactive atoms left after decaying during T time

Input the value :

$\tt 2.5=40.\dfrac{1}{2}^{t/5730}\\\\\dfrac{2.5}{40}=\dfrac{1}{2}^{t/5730}\\\\(\dfrac{1}{2})^4=\dfrac{1}{2}^{t/5730}\\\\4=t/5730\rightarrow t=22920~years$

You might be interested in

The atomic number of polassium and

never [62]

Explanation:

Atomic radius decreases from left to right in a period.

Therefore Calcium would have a smaller atomic size.

6 0

3 years ago

13.8g element consist 4.6 ×10^22 atoms what is atomic mass of element?

Keith_Richards [23]

<h2>~<u>Solution</u> :-</h2>

Here, to find the atomic mass of element, we must;

We know that,

4.6 x $ \sf{10^{22}}$ atoms of an element weigh 13.8g.

Thus,

The atoms of $ \sf{ 6.02 \times 10^{13}}$ will weigh;

$= \sf{\frac{13.8 \times 6.02 \times {10}^{23} }{4.6 \times {10}^{22} } } \\$

$= \sf{180.6 \: g \: \: (molar \: mass)}$

Hence, the molar mass (atomic mass) will be <u>180.6 g.</u>

8 0

3 years ago

Read 2 more answers

Over the years, the thermite reaction has been used for welding railroad rails, in incendiary bombs, and to ignite solid-fuel ro

melamori03 [73]

<u>Answer:</u> The mass of nickel (II) oxide and aluminium that must be used is 18.8 g and 4.54 g respectively.

<u>Explanation:</u>

To calculate the number of moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$ .....(1)

<u>For nickel:</u>

Given mass of nickel = 14.8 g

Molar mass of nickel = 58.7 g/mol

Putting values in equation 1, we get:

$\text{Moles of nickel}=\frac{14.8g}{58.7g/mol}=0.252mol$

For the given chemical reaction:

$3NiO(s)+2Al(s)\rightarrow 3Ni(l)+Al_2O_3(s)$

<u>For nickel (II) oxide:</u>

By Stoichiometry of the reaction:

3 moles of nickel are produced from 3 moles of nickel (II) oxide

So, 0.252 moles of nickel will be produced from $\frac{3}{3}\times 0.252=0.252mol$ of nickel (II) oxide

Now, calculating the mass of nickel (II) oxide by using equation 1:

Molar mass of nickel (II) oxide = 74.7 g/mol

Moles of nickel (II) oxide = 0.252 moles

Putting values in equation 1, we get:

$0.252mol=\frac{\text{Mass of nickel (II) oxide}}{74.7g/mol}\\\\\text{Mass of nickel (II) oxide}=(0.252mol\times 74.7g/mol)=18.8g$

<u>For aluminium:</u>

By Stoichiometry of the reaction:

3 moles of nickel are produced from 2 moles of aluminium

So, 0.252 moles of nickel will be produced from $\frac{2}{3}\times 0.252=0.168mol$ of aluminium

Now, calculating the mass of aluminium by using equation 1:

Molar mass of aluminium = 27 g/mol

Moles of aluminium = 0.168 moles

Putting values in equation 1, we get:

$0.168mol=\frac{\text{Mass of aluminium}}{27g/mol}\\\\\text{Mass of aluminium}=(0.168mol\times 27g/mol)=4.54g$

Hence, the mass of nickel (II) oxide and aluminium that must be used is 18.8 g and 4.54 g respectively.

4 0

3 years ago

What unusual thing can the bull shark do?

kotegsom [21]

Bull sharks have the unique ability of keeping salt in their bodies even freshwater

3 0

3 years ago

Which beaker has the least thermal energy?

Debora [2.8K]

Answer:

Breaker A

Explanation:

Because the temperature is cooler in A then the rest

3 0

3 years ago

Read 2 more answers