How many grams of ^16N will be left from a 16.0 g sample after 21.6 s?

2 g

Explanation:

From the question given above, the following data were obtained:

Original amount (N₀) = 16 g

Time (t) = 21.6 s

Amount remaining (N) =?

Next, we shall determine the number of half-lives that has elapse. This can be obtained as follow:

Time (t) = 21.6 s

Half-life (t½) of ¹⁶N = 7.13 s

Number of half-lives (n) =?

n = t / t½

n = 21.6 / 7.13

n = 3

Finally, we shall determine the amount of ¹⁶N remaining. This can be obtained as follow:

Original amount (N₀) = 16 g

Number of half-lives (n) = 3

Amount remaining (N) =?

N = 1/2ⁿ × N₀

N = 1/2³ × 16

N = 1/8 × 16

N = 2 g

Thus, the amount of ¹⁶N remaining is 2 g

answer: enthalpy

explanation:

for a exothermic reaction, the energy is released i.e. the energy of the products is lower than the energy of the reactants.

= enthaply

= energy of products

= energy of reactants

as , thus comes out to be negative. negative value of enthalpy shows that the reaction is exothermic.

explanation:

let the different atoms be x and y. each with four protons and same mass will be represented as follows.

mass number is number of protons + number of neutrons.

            and  

since, it is given that one has a negative charge while the other is neutral. therefore, there will be increase in number of protons and the atom will be represented as follows.

according to periodic table, mass number of beryllium is 9 and it has atomic number 4 so, the atoms will be and .  

the protons and neutrons will be located inside the nucleus whereas the electrons will be revolving around the nucleus.