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3 years ago

HELP with these 2 questions asap

Chemistry

2 answers:

Allisa [31]3 years ago

8 0

Answer: For question one...B. Because cells are too small to see without a microscope. It would have been impossible because cells are hard to deal with without a microscope because they are so tiny. So, without it, he wouldn't have been able to get the answer out of his discovery.

For question two...D. The nucleus is the control center of the cell. The cell theory states that, for 1., All living things are made of cells and their product., 2. New cells are created by only old cells dividing into two, and 3. Cells are he basic units of life. Cells having a nucleus is not mentioned and will never be because, cells don't need a nucleus to keep moving or keep the cell in control.

I hope this helps you! I really do hope it does.

katovenus [111]3 years ago

5 0

Answer:

number 1 is b and and number two d

Explanation:

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The mass of a watch glass was measured four times. The masses were

tigry1 [53]

To get the mass of the glass watch. It’s very simple. Take all 4 numbers 99.997, 100.008, 100.011, 100.005 add them together and then divide them by 4 bc there were 4 numbers to begin with.
The mass of the glass is- 100.00525 g

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3 years ago

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Nitrous acid, hno2, has a ka of 7. 1 ✕ 10-4. what are [h3o ], [no2-], and [oh -] in 0. 40 m hno2?

romanna [79]

Nitrous acid, hno2, has an acid dissociation constant - ka of 7. 1 ✕ 10-4. what are [h3o ], [no2-], and [oh -] in 0. 40 m hno2 - 4829 M [OH^-] = 1.439 x 10^-14 M

The acid dissociation constant (Ka) is used to differentiate between strong and weak acids. Strong acids have very high Ka values. The Ka value is determined by examining the equilibrium constant for acid dissociation. The acid dissociates more readily as the Ka increases.

The original molecular definition of an acid, according to Arrhenius, is a molecule that dissociates in an aqueous solution, releasing the hydrogen ion H+ (a proton): HA A + H+. acid dissociation constant is an equilibrium constant for this dissociation reaction.

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1 year ago

What volume (ml) of fluorine gas is required to react with 1. 28 g of calcium bromide to form calcium fluoride and bromine gas a

Alexandra [31]

144 mL of fluorine gas is required to react with 1.28 g of calcium bromide to form calcium fluoride and bromine gas at STP.

<h3>What is Ideal Gas Law ? </h3>

The ideal gas law states that the pressure of gas is directly proportional to the volume and temperature of the gas.

PV = nRT

where,

P = Presure

V = Volume in liters

n = number of moles of gas

R = Ideal gas constant

T = temperature in Kelvin

Here,

P = 1 atm [At STP]

R = 0.0821 atm.L/mol.K

T = 273 K [At STP]

Now first find the number of moles

F₂ + CaBr₂ → CaF₂ + Br₂

Here 1 mole of F₂ reacts with 1 mole of CaBr₂.

So, 199.89 g CaBr₂ reacts with = 1 mole of F₂

1.28 g of CaBr₂ will react with = n mole of F₂

$n = \frac{1.28\g \times 1\ \text{mole}}{199.89\ g}$

n = 0.0064 mole

Now put the value in above equation we get

PV = nRT

1 atm × V = 0.0064 × 0.0821 atm.L/mol.K × 273 K

V = 0.1434 L

V ≈ 144 mL

Thus from the above conclusion we can say that 144 mL of fluorine gas is required to react with 1.28 g of calcium bromide to form calcium fluoride and bromine gas at STP.

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1 year ago

Calculate the heat absorbed by a sample of water that has a mass of 45.00 g when the temperature increases from 21.0oC to 38.5 o

Elenna [48]

Answer:

The heat absorbed by the sample of water is 3,294.9 J

Explanation:

Calorimetry is the measurement and calculation of the amounts of heat exchanged by a body or a system.

The sensible heat of a body is the amount of heat received or transferred by a body when it undergoes a temperature variation (Δt) without there being a change of physical state (solid, liquid or gaseous). Its mathematical expression is:

Q = c * m * ΔT

Where Q is the heat exchanged by a body of mass m, made up of a specific heat substance c and where ΔT is the temperature variation.

In this case:

Q=?
m= 45 g
c= 4.184 $\frac{J}{g*C}$
ΔT= Tfinal - Tinitial= 38.5 C - 21 C= 17.5 C

Replacing:

Q= 4.184 $\frac{J}{g*C}$ * 45 g* 17.5 C

Solving:

Q=3,294.9 J

<u><em>The heat absorbed by the sample of water is 3,294.9 J</em></u>

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3 years ago

When is a hurricane nears land, causes the most damage?

xeze [42]

A hurricane will weaken after making landfall.

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2 years ago