All categories

3 years ago

What is the total number of neutrons in an atom of an element that has a mass number of 19 and an atomic number of 9?

1 answer:

7 0

Your answer should be B.) 10

The atomic mass of an element is the sum of the element's protons and neutrons. The atomic number of an element is equal to its number of protons. To find the amount of neutrons in an atom, subtract the atomic number from the atomic mass. 19 - 9 = 10.

Hope this helps!

You might be interested in

Choose one of these three people and write a letter to them to express your concerns about the events of 01/06/21

Mashcka [7]

Bro I didn’t put nothing

6 0

3 years ago

You are part of a design team assigned the task of making an electronic oscillator that will be the timing mechanism of a micro-

Snowcat [4.5K]

Solution :

We assume that there is a ring having a charge +Q and radius r. Electric field due to the ring at a point P on the axis is given by :

$E_P=\int dE \cos$

$E_P=\int \frac{KdQ}{(\sqrt{r^2+x^2})^2}\times \frac{x}{\sqrt{r^2+x^2}}$

$\vec{E_P}=\frac{Kx}{r^2+x^2} \int dQ$

$\vec{E_P}=\frac{KxQ}{(r^2+x^2)^{3/2}} \hat{i}$

If we put an electron on point P, then force on point e is :

$\vec{F}=-|e|\vec{E_P}$

$F= \frac{-eKQx}{(r^2+x^2)^{3/2}}= \frac{-eKQx}{r^3[1+\frac{x^2}{r^2}]^{3/2}}$

If r >> x , then $\frac{x^2}{r^2} \approx 0$

Then, $\frac{-eKQ}{r^3}x$

$ma =\frac{-eKQ}{r^3}x$

$a =\frac{-eKQ}{mr^3}x$

Compare, a = -ω²x

We get,

$\omega^2 = \frac{eKQ}{R^3m}$

$\omega = \sqrt{\frac{eKQ}{r^3m}}$

$2 \pi f = \sqrt{\frac{eKQ}{r^3m}}$

$f = \frac{1}{2 \pi}\sqrt{\frac{eKQ}{mr^3}}$

6 0

3 years ago

A schoolbus accelerates to 65 mph and enters the freeway. It travels for 2.3 hours at that speed while on the freeway. What's th

PtichkaEL [24]

Answer:

The distance travelled on the freeway is 149.5 miles.

Explanation:

The school bus travels on the freeway at constant speed. According to the statement, we need to calculate the distance travelled by the vehicle by means of the following formula:

$x = v\cdot t$ (1)

Where:

$x$ - Traveled distance, in miles.

$v$ - Speed, in miles per hour.

$t$ - Time, in hours.

If we know that $v = 65\,\frac{mi}{h}$ and $t = 2.3\,h$ , then the distance travelled by the school bus is:

$x = v\cdot t$

$x = \left(65\,\frac{mi}{h} \right)\cdot (2.3\,h)$

$x = 149.5\,mi$

The distance travelled on the freeway is 149.5 miles.

5 0

3 years ago

At a certain instant, the speedometer of the car indicates 80 km/h.

Scorpion4ik [409]

Answer:

It tells the speed of car. At this time the speed of car is 80km/h , means if the car runs constantly at this speed then it will cover 80 kilometres in 1 hour.