All categories

3 years ago

If an isotope of an element has 40 neutrons and a mass number of 79, how many electrons must it have?

Chemistry

1 answer:

34kurt3 years ago

5 0

Answer: 39 electrons

Explanation: Subtract 79 by 40 to get the atomic number (amount of protons) which is 39. The number of electrons must be the same as the number of protons if it's not an ionic compound so the amount of electrons is the same amount of protons.

You might be interested in

Climates are classified acording to which two major factors

Oxana [17]

Precipitation and temperature

4 0

3 years ago

List the two factors used to calculate force ? (20 pionts)

Yuliya22 [10]

Answer:The strength of the gravitational force between two objects depends on two factors, mass and distance. the force of gravity the masses exert on each other.

Explanation: i hope it answers your question

5 0

3 years ago

Read 2 more answers

How many moles are in 35.0 grams of H₂O?

Nikitich [7]

1.94 moles

I did 35/18.02 because 18.02 is the molar mass of water

3 0

3 years ago

The reaction of NO2 with ozone produces NO3 in a second-order reaction overall.

Brilliant_brown [7]

Answer : The rate of reaction is,

$Rate=4.77\times 10^{-19}M/s$

The appearance of $NO_3$ is, $4.77\times 10^{-19}M/s$

Explanation :

The general rate of reaction is,

$aA+bB\rightarrow cC+dD$

Rate of reaction : It is defined as the change in the concentration of any one of the reactants or products per unit time.

The expression for rate of reaction will be :

$\text{Rate of disappearance of A}=-\frac{1}{a}\frac{d[A]}{dt}$

$\text{Rate of disappearance of B}=-\frac{1}{b}\frac{d[B]}{dt}$

$\text{Rate of formation of C}=+\frac{1}{c}\frac{d[C]}{dt}$

$\text{Rate of formation of D}=+\frac{1}{d}\frac{d[D]}{dt}$

$Rate=-\frac{1}{a}\frac{d[A]}{dt}=-\frac{1}{b}\frac{d[B]}{dt}=+\frac{1}{c}\frac{d[C]}{dt}=+\frac{1}{d}\frac{d[D]}{dt}$

From this we conclude that,

In the rate of reaction, A and B are the reactants and C and D are the products.

a, b, c and d are the stoichiometric coefficient of A, B, C and D respectively.

The negative sign along with the reactant terms is used simply to show that the concentration of the reactant is decreasing and positive sign along with the product terms is used simply to show that the concentration of the product is increasing.

The given rate of reaction is,

$NO_2(g)+O_3(g)\rightarrow NO_3(g)+O_2(g)$