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3 years ago

The nucleus of an atom holds 4 neutrons and 4 protons, how many electrons does it have

Chemistry

1 answer:

sweet-ann [11.9K]3 years ago

6 0

It has 4 electrons, because the number of protons and the number of electrons must be equal.

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Consider the laboratory on HPLC analysis of components in diet soft drinks. Your standard solutions for caffeine were prepared f

borishaifa [10]

Answer:

i dont know they made me do it! sorry!!!

Explanation:

7 0

3 years ago

What is the amount, in moles, of each elemental sample? a. 11.8 g Ar b. 3.55 g Zn c. 26.1 g Ta d. 0.211 g Li

spayn [35]

Answer:

A. 0.295 mole

B. 0.055 mole

C.0.144 mole

D. 0.03 mole

Explanation:

To find the amount in moles, we simply use a mathematical relation that connects mass, atomic mass and number of moles.

Number of moles = mass/atomic mass

A. Atomic mass of Argon is 40

n = 11.8/40 = 0.295 mole

B. Atomic mass of zinc is 65

n = 3.55/65 = 0.055 mole

C. Atomic mass of Tantalum is 181

n = 26.1/181 = 0.144 mole

D. Atomic mass of lithium is 7

n = 0.211/7 = 0.03 mole

8 0

3 years ago

The stopper-puncturing needle should be completely pushed into the evacuated tube:__________. A. after the vein is entered. B. w

brilliants [131]

Answer:

The correct answer is:

after the vein is entered (A.)

Explanation:

The procedure in the question describes venopuncture.

Venopuncture is the method of aseptically collecting blood into the right sample containers. Using a stopper-punturing needle and a vacuum tube, the following procedure is followed:

assemble the needle and hub (needle holder)
apply the tourniquet and examine the arm for palpable vein, palpate the vein
release the tourniquet and swab the collection site with 70% alcohol
allow the swab to dry
reapply the tourniquet
insert the stopper-puncturing needle (attached to hub) into the appropriate vein
after the vein is entered, the stopper-puncturing needle should be completely pushed into the evacuated (vacuum) tubes
blood will flow into the tube until vacuum is completely filled
pull out the tube and invert gently several times if the tube contains anticoagulants
place a gauze on the site of puncture (do not press down the gauze)
remove the needle and press down the gauze immediately
dispose the needle into the sharps container or appropriately
label the tubes.

6 0

3 years ago

You are on vacation with your family up in the mountains. your friend is on vacation near the equator by the ocean.Explain which

kirill115 [55]

Answer:

option d is right

Explanation:

More precipitation occurs near the equator because it is a tropical area. Mountains receive less than 15 inches of rain per year while the equator area receives a lot of rain. This is due to the very hot weather.

8 0

3 years ago

At a certain temperature a 42.55% (v/v) solution of ethyl alcohol, C2H5OH, in water has a density of 0.9027 g mL-1. The density

swat32

Answer:

a. 7.187M.

b. 7.962m.

c. 0.1846

Explanation:

This solution contains 42.55mL of ethyl alcohol in 100mL of solution.

a. Molar concentration = Moles ethyl alcohol / L solution:

Moles ethyl alcohol -Molar mass: 46.07g/mol-

42.55mL * (0.7782g/mL) * (1mol / 46.07g) = 0.7187 moles ethyl alcohol

Liters solution:

100mL * (1L / 100mL) = 0.100L

Molar concentration: 0.7187mol / 0.100L = 7.187M

b. Molal concentration: Moles ethyl alcohol (0.7187moles) / kg solution

kg solution:

100mL * (0.9027g / mL) * (1kg / 1000g) = 0.09027kg

Molal concentration: 0.7187mol / 0.09027kg = 7.962m

c. Mole fraction: Moles ethyl alcohol / Moles ethyl alcohol + moles water

Moles water: -molar mass: 18.01g/mol-

Volume water = 100mL - 42.55mL = 57.45mL

57.45mL * (0.9949g/mL) * (1mol/18.01g) = 3.1736 moles water

Moles fraction:

0.7187 moles ethyl alcohol / 0.7187 moles ethyl alcohol+3.1736 moles water

= 0.1846

4 0

3 years ago