What mass of a 60.0-gram sample of N-16 will remain unchanged after 28.8 seconds?

Answers

Answer 1

Answer: The answer is 3.75 g.

Half-life is the time required for the amount of a sample to half its value.
To calculate the fraction of the sample remained unchanged, we will use the following formulas:
1. $(1/2)^(n) = x$ ,
where:
n - a number of half-lives
x - a remained fraction of a sample

2. $t_(1/2) = (t)/(n)$
where:
$t_(1/2)$ - half-life
t - total time elapsed
n - a number of half-lives

The half-life of N-16 is 7.13.
So, we know:
t = 28.8 s
$t_(1/2)$ = 7.13 s

We need:
n = ?
x = ?

We could first use the second equation, to calculate n:
If:
$t_(1/2) = (t)/(n)$ ,
Then:
$n = (t)/( t_(1/2) )$
⇒ $n = (28.8 s)/(7.13 s)$
⇒ $n=4.04$
⇒ n ≈ 4

Now we can use the first equation to calculate the remained amount of the sample.
$(1/2)^(n) = x$
⇒ $x=(1/2)^4$
⇒ $x= (1)/(16)$

If the fraction of the sample is 1/16 = 6.25%, then the mass of the sample could be calculated as:
x g : 6.25% = 60 g : 100%
x =

The answer is 4 because when the vapor pressure is in liquid form, the boiling point would be the hottest point

What is the role of microbes in maintain temperature on earth? (Role of microbes in CO2 and CH4recycling)

Answers

Answer:

Explanation:

As the bacteria are capable of surviving in the hot temperatures as thermophiles they can speed up their respiration rate and hence, will produce more carbon dioxide and potentially accelerating the climate change within a region. The other prokaryotes can also become the significant contributors of the carbon output and these are those which are highly sensitive to the temperature. Methane oxidizing bacteria are also responsible for the contribution in carbon and nitrogen cycles. These bacteria converts the important greenhouse gas methane into carbon and nitrogen compounds like CO2 and NO2 − respectively. Thus methane can be considered as precursor of the temperature rise.

Complete the balanced equation: Cu(NO3)2 + Na2CO3 > ?

Answers

I think its CuCO3+NaNO3 but idk if its right

Which element is classified as an alkali metal?
Rb
Sr
Zr
Cl

Answers

Hi there.

Alkali metals are known as the group 1 elements.

When we know this, we just have to look to group 1 of the periodic table.

Rb (Rubidium) is in group 1; it is classified as an alkali metal.

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Answer:

Explanation:

on edge

Boron occurs naturally as two isotopes. What is the difference between these isotopes? a)They have different numbers of electrons and different charges.
b)They have different numbers of neutrons and different charges.
c)They have different numbers of protons and different mass numbers.
d)They have different numbers of neutrons and different mass numbers.

Answers

atoms are made of 3 types of subatomic particles that are electrons, protons and neutrons.
the number of protons in the atom is called the atomic number. the atomic number is characteristic of the element.
the mass number is the sum of the number of protons and neutrons. Since protons and neutrons both have similar masses and they are located in the nucleus, the mass of the atom is the sum of protons and neutrons.
Isotopes are when 2 atoms of the same element have different number of neutrons. Therefore atomic number is the same but mass number is different as the number of neutrons vary.

correct answer for the difference between isotopes is
d)They have different numbers of neutrons and different mass numbers.

Boron occurs naturally as two isotopes that is they have the same number of protons and different numbers of neutrons with different atomic charges. Option D is correct.

What are isotopes?

These are the variations of elements having the same number of protons and electrons and different numbers of neutrons. As they are neutral in charge and their mass is totally negligible as compared to the mass of proton as they both are located at the center of the atom

The center of the atom is the nucleusas there are some more species of element isobars isotones isoelectronic. Isobars are those species that have the same neutronic numbers with different photonic and electronic numbers

The isotopes of boron are boron10, boron12, boron14, etc. .Carbon is another compound that is having 3 isotopes carbon12 carbon13, and caobon14. But mostly their properties are the same with a little difference between them

Therefore, the correct option is D.

Learn more about isotopes, here:

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calculate the mass required to prepare 2.5 L of 1.0 M NaOH solution. Given that the molar mass for NaOH is 40 g/mol.

Answers

Answer:

$100\; \rm g$ of ${\rm NaOH}\; (s)$ would be required.

Explanation:

The quantity of solute in a solution of concentration $c$ and volume $V$ would be $n = c \cdot V$ .

It is given that volume $V = 2.5\; \rm L$ for the solution in this question. It is also given that the concentration of the $\rm NaOH$ solute in this solution is $c = 1.0\; \rm M$ , which is the equivalent to $c = 1.0\; \rm mol \cdot L^(-1)$ .