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sergeinik [125]

3 years ago

12

Determine the number of protons and neutrons in an isotope of bromine (br) with a mass number/atomic mass of 79. (the atomic num

ber of bromine is 35.)

1 answer:

miskamm [114]3 years ago

8 0

44 neutrons and 35 protons. The number of neutrons you have is equal to the atomic mass minus the atomic number.

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Find the percent composition for SF6<br> S =? %<br> F =? %

goldenfox [79]

Answer:

S = 21.92 %

F = 78.08 %

Explanation:

To find the percent composition of each element in SF6, we must find the molar mass of SF6 first.

Molar mass of SF6 = 32 + 19(6)

= 32 + 114

= 146g/mol

mass of Sulphur (S) in SF6 = 32g

mass of Fluorine (F) in SF6 = 114g

Percent composition = mass of element/molar mass of compound × 100

- % composition of S = 32/146 × 100 = 21.92%.

- % composition of F = 114/146 × 100 = 78.08%.

6 0

2 years ago

Is an apple a pure substance or a mixture?

guajiro [1.7K]

An apple would be a mixture. While a mixture is a combination of elements and substances, a pure substance acts as an element itself, therefore, having the properties of only THAT certain element.

6 0

3 years ago

Read 2 more answers

Meet /svc-jgyu-fii<br>join

arsen [322]

Answer:

what are we doing there???

bye, have a nice day!

5 0

3 years ago

It takes 281.7 kJ of energy to remove 1 mole of electrons from the atoms on the surface of lithium metal. If lithium metal is ir

Alex17521 [72]

Answer:

The maximum kinetic energy of electron is = 2.93 × $10^{-19}$ Joule

Explanation:

We know that total energy

$E = \frac{hc}{\lambda}$ ------------ (1)

Here h = plank's constant = 6.62 × $10^{-34}$ J s

c = speed of light = 3 × $10^{8}$ $\frac{m}{s}$

$\lambda$ = 261 nm = 261 × $10^{-9}$ m

Put all these values in equation (1) we get

E = 7.6 × $10^{-19}$ J

We know that

Total energy = Energy to remove an electron + K.E of electron

Energy to remove an electron = $\frac{281.7 (1000)}{(6.023)10^{23} }$

Energy to remove an electron = 4.67 × $10^{-19}$ J

K.E of electron = Total energy - Energy to remove an electron

K.E of electron = 7.6 × $10^{-19}$ - 4.67 × $10^{-19}$

K.E of electron = 2.93 × $10^{-19}$ Joule

Therefore the maximum kinetic energy of electron is = 2.93 × $10^{-19}$ Joule

3 0

3 years ago

One mole of a substance has the same number of particles as one mole of any other substance, regardless of what substances are b

katen-ka-za [31]

This is a true statement

3 0

2 years ago