Option no. 2 subtracting the atomic number from the mass number

Example: Zn - 65 atomic weight or mass/mass number
30 atomic number

65-30 = 35 number of neutrons

5 0

2 years ago

PLEASE HELP!!!!! NEED THE ANSWER FAST!!!

PIT_PIT [208]

The answer is a. changes in nucleotides of a DNA molecule that affect the genetic message.

6 0

3 years ago

How many particles are present in 12.47 grams of NaCl

liq [111]

Answer:

1.26*10²³ particles are present in 12.47 grams of NaCl

Explanation:

Avogadro's Number or Avogadro's Constant is called the number of particles that make up a substance (usually atoms or molecules) and that can be found in the amount of one mole of said substance. Its value is 6.023 * 10²³ particles per mole. The Avogadro number applies to any substance.

So, first of all you must know the amount of moles that represent 12.47 grams of NaCl. For that it is necessary to know the molar mass.

You know:

Na: 23 g/mole
Cl: 35.45 g/mole

So the molar mass of NaCl is: 23 g/mole + 35.45 g/mole= 58.45 g/mole

Now you apply a rule of three as follows: if 58.45 grams are present in 1 mole of NaCl, 12.47 grams in how many moles will they be?

$moles=\frac{12.47 grams*1 mole}{58.45 grams}$

moles= 0.21

You apply a rule of three again, knowing Avogadro's number: if in 1 mole of NaCl there are 6,023 * 10²³ particles, in 0.21 moles how many particles are there?

$number of particles=\frac{0.21 moles*6.023*10^{23} }{1 mole}$

number of particles= 1.26*10²³

1.26*10²³ particles are present in 12.47 grams of NaCl

5 0

3 years ago