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zheka24 [161]
2 years ago
8

How have observations in the sky enabled humans to explore and travel?

Chemistry
1 answer:
andre [41]2 years ago
4 0

Answer:

Observations of the sky allowed explorers to mark the passage of time both in hours and through the months of the year. Early astronomers also realized that the night sky does not look the same from different places on the Earth.

You might be interested in
What is made when a salt is dissolved in water?
Xelga [282]

Answer:

D. A solution.

Explanation:

"Water molecules pull the sodium and chloride ions apart, breaking the ionic bond that held them together. After the salt compounds are pulled apart, the sodium and chloride atoms are surrounded by water molecules, as this diagram shows. Once this happens, the salt is dissolved, resulting in a homogeneous solution."

3 0
2 years ago
A student collects 350 mL of a vapor at a temperature of 67°C. The atmospheric pressure at the time of collection is 0.900 atm.
Fed [463]

Answer:

Explanation:

This problem is very similar to the other that you put before, so, we'll use the same principle here.

The ideal gas equation: PV = nRT

Where:

P: pressure in atm

V: volume in L

T: Temperature in K.

n: moles

R: Gas constant (In this case, we'll use 0.082 L atm/K)

to get the molar mass of the gas, we need to know the moles, and with the mass, we can know the molar mass. However we can put the ideal gas expression with the molar mass in this way:

we know that n is mole so:

n = g/MM

If we put this in the idea gases expression we have:

PV = gRT/MM

Solving for MM we have:

MM = gRT/PV

Now, let's convert the temperature and volume to K and L respectively:

T = 67 + 273 = 340 K

V = 350 / 1000 = 0.35 L

Now all we have to do is put all the data into the expression:

MM = 0.79 * 0.082 * 340 / 0.9 * 0.35

MM = 22.0252 / 0.315 = 69.92 g/mol rounded 70 g/mol

Now, the closest answer of your options would be 72 g/mol. This could be easily explained because we do not use all the significant figures of all numbers, including the gas constant of R. However, all the work, calculations and procedure is correct and fine, and we only have a minimum range of 2 units.

6 0
3 years ago
how much heat, in terms in q, would it take to produce the change in temperature indicated in the picture? what is your reasonin
STALIN [3.7K]

Answer:

1. q.

2. 2q.

3. 3q.

4. 6q.

Explanation:

We'll begin by calculating the specific heat capacity of the liquid. This can be obtained as follow:

Mass (m) = 25 g

Change in temperature (ΔT) = 20 °C

Heat (Q) = q

Specific heat capacity (C) =?

Q = MCΔT

q = 25 × C × 20

q = 500C

Divide both side by 500

C = q/500

C = 2×10¯³ qg°C

Therefore, the specific heat capacity of liquid is 2×10¯³ qg°C

Now, we shall determine the heat required to produce the various change in temperature as follow:

2. Mass (m) = 50 g

Change in temperature (ΔT) = 20 °C

Specific heat capacity (C) = 2×10¯³ qg°C

Heat (Q) =?

Q = MCΔT

Q = 50 × 2×10¯³ × 20

Q = 2q.

Therefore, the heat required is 2q.

3. Mass (m) = 25 g

Change in temperature (ΔT) = 60 °C

Specific heat capacity (C) = 2×10¯³ qg°C

Heat (Q) =?

Q = MCΔT

Q = 25 × 2×10¯³ × 60

Q = 3q.

Therefore, the heat required is 3q.

4. Mass (m) = 50 g

Change in temperature (ΔT) = 60 °C

Specific heat capacity (C) = 2×10¯³ qg°C

Heat (Q) =?

Q = MCΔT

Q = 50 × 2×10¯³ × 60

Q = 6q.

Therefore, the heat required is 6q.

4 0
2 years ago
A student fires a bow and arrow in gym class and all his arrows land close to each other, but not on the bullseye. This student
dimulka [17.4K]
A student fires a bow and arrow in gym class and all his arrows land close to eachother but not on the bullseye. this student could be said to be:

precise but not accurate

4 0
2 years ago
What is the molarity when 0.181 moles of MgNO3)2 are dissolved in enough water to make 0.750 L solution?
eimsori [14]

Answer:

Molarity = 0.24 M

Explanation:

Given data:

Number of moles of Mg(NO₃)₂ = 0.181 mol

Volume of solution = 0.750 L

Molarity of solution = ?

Solution:

Molarity is used to describe the concentration of solution. It tells how many moles are dissolve in per litter of solution.

Formula:

Molarity = number of moles of solute / L of solution

by putting values,

Molarity = 0.181 mol / 0.750 L

Molarity = 0.24 M

4 0
2 years ago
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