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3 years ago

I need help please quick I’m female 15

Chemistry

2 answers:

Reptile [31]3 years ago

6 0

Answer: I believe it is A.

Explanation:

alexandr1967 [171]3 years ago

3 0

Answer:

A homogeneous mixture with compounds of varying density

Explanation:

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A proton is a subatomic particle carrying a charge equal to but opposite that of an electron

Pachacha [2.7K]

Answer:

True

Explanation:

A proton has a charge of +1, while an electron has a charge of -1. This is why a neutral atom has the same number of protons as electrons.

Neutrons have no charge, hence their name neutron which is similar to neutral.

8 0

3 years ago

9. When you move your hand from a hot stove what is the stimulus you are reacting to?

Gemiola [76]

Answer:

if you touch a hot stove, the nerves in your skin shoot a message of pain to your brain. The brain then sends a message back telling the muscles in your hand to pull away.

Explanation:

4 0

2 years ago

how many grams of antifreeze would be required per 500 g of water to prevent the water from feezing at a temperature of -39° C

andrezito [222]

Answer:

333.7g of antifreeze

Explanation:

Freezing point depression in a solvent (In this case, water) occurs by the addition of a solute. The law is:

ΔT = Kf × m × i

Where:

ΔT is change in temperature (0°C - -20°C = 20°C)

Kf is freezing point depression constant (1.86°C / m)

m is molality of solution (moles solute / 0.5 kg solvent -500g water-)

i is Van't Hoff factor (1, assuming antifreeze is ethylene glycol -C₂H₄(OH)₂)

Replacing:

20°C = 1.86°C / m × moles solute / 0.5 kg solvent × 1

5.376 = moles solute

As molar mass of ethylene glycol is 62.07g/mol:

5.376 moles × (62.07g / 1mol) = <em>333.7g of antifreeze</em>.

4 0

3 years ago

When aluminum is placed in concentrated hydrochloric acid, hydrogen gas is produced. 2 Al ( s ) + 6 HCl ( aq ) ⟶ 2 AlCl 3 ( aq )

Dovator [93]

Answer:

The volume of hydrogen gas produced at STP is 4.90 liters.

Explanation:

$2Al (s) + 6 HCl (aq)\rightarrow 2 AlCl_3 (aq) + 3 H_2 (g)$

Moles of aluminium = $\frac{3.60 g}{27 g/mol}=0.1333 mol$

According to reaction , 2 moles of aluminium gives 3 moles of hydrogen gas.

Then 0.1333 moles of aluminium will give:

$\frac{3}{2}\times 0.1333 mol=0.2 moles$ of hydrogen gas

Volume of 0.2 moles of hydrogen gas at STP = V

Temperature at STP = T = 298.15 K

Pressure at STP = P = 1 atm

n = 0.2 mol

PV = nRT (Ideal gas equation)

$V=\frac{nRT}{P}=\frac{0.2mol\times 0.0821 atm L/mol K\times 298.15 K}{1 atm}=4.8956 L\approx 4.90 L$

The volume of hydrogen gas produced at STP is 4.90 liters.

4 0

3 years ago

Serial dilution problem: Six test tubes are placed in a rack. To each tube add 4 mL of saline solution. Now to the first tube ad

ArbitrLikvidat [17]

Answer:

The dilution factor of protein in tube # 4 is 125. Molar concentration is 0.0088 M protein

Explanation:

The dilution factor indicates how many times is more concentrated a main solution in relationship with a diluted solution. In this case, the main solution is in tube #1. For calculating the dilution factor and molar concentration in tube #4 we need the main solution concentration which comes from next equation:

Initial volume * initial concentration = final volume * final concentration

0.5 mL * 10M = 5mL * final concentration

1.1 M = final concentration = main solution concentration

Applying the same equation for remain tubes we have 0.22 M for tube #2, 0.044 M for tube # 4 and 0.0088 for tube # 4.

Dilution factor = Main solution concentration/tube 4 concentration

Dilution factor = 1.1/0.0088 = 125

I hope my answer helps you

3 0

3 years ago