CHEMISTRY MIDDLE SCHOOL

In chemistry, the most commonly used unit of concentration is

Answers

Answer 1
Answer:

Answer: Molarity

Explanation:

Molarity

Molarity is the most common concentration unit involved in calculations dealing with volumetric stoichiometry. Molality (m): This unit of concentration relates the moles of solute per kilogram of solvent.


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HIGH SCHOOL

In Nuclear chemistry, the key requirement for a chain reaction is that...a. each event must produce more than one particle capable of initiating subsequent events.b. the number of beta particles emitted must be equal to or greater than the number of gamma particles emitted.c. the entropy of the system must decrease.d. the uranium hexafluoride fuel must be in its solid state.

Answers

Cccccccccccccccccccccccc

MIDDLE SCHOOL

Which of the following indicates a change in the chemical properties of matter? A.Precipitate formation B.Change in heat energy C.Butter melting D.Both A and B

Answers

Answer:

A.Precipitate formation

Explanation:

During the precipitation two liquid combine and solid is formed. This solid is called precipitate. The formation of precipitation involve chemical reaction that's why it changes the chemical properties of matter.

Chemical change:

The changes, that occur due to change in the composition of a substance and result in a different compound is known as chemical change.

These changes are irreversible

These changes occur due to chemical reactions

These may not be observed with naked eye

Example:

Combustion of fuel or wood: that oil or wood convert into energy, CO2 and ash in case of wood

Boiling of egg: that change the chemical composition of protein in the egg .

The reaction of Hydrogen and oxygen:

H 2 (g)  + O 2  (g) -------------------------------------> 2H 2O  (l)

Answer: D. both A and B

Explanation:

I took the CK-12

MIDDLE SCHOOL

Which soil horizon contains a layer of partially weathered or unweathered rock? A. E
B. R
C. O
D. C

Answers

Answer:

B.  R

Explanation:

A layer of partially weathered or unweathered rock is present in R soil horizon

Answer: Option (B)

Explanation: The R-layer represents the unweathered rocks that are located below the surface and is the lowest layer in the soil profile. Here, hard rocks are found which are difficult to break, and are breakable with heavy machineries only. This R-layer makes the foundation of the soil profile that supports the entire overlying series of layers.

Thus, the correct answer is option (B).

MIDDLE SCHOOL

Explain why energy has to be supplied to turn a liquid into a gas

Answers

When liquid converts to gas then heat is required to break the intermolecular forces of attraction between the particles. In this process heat increase but temperature remains the same.

What is phase transition?

Phase transition is a process in which transition takes place from one state to another of a medium on changing temperature or pressure. Phase transition is a physical process as there is no breaking of old bond and forming of new bonds takes place.

During phase transition temperature remain constant as the extra heat that is given to the system that goes into breaking of intermolecular forces of attraction between the particles. So overall temperature remains same but heat keeps on increasing.

Therefore, energy has to be supplied to turn a liquid into a gas to break the intermolecular forces of attraction between the particles.

To learn more about phase transition, here:

brainly.com/question/3255181

#SPJ2

Answer:

heat energy are absorbed by water molecules and it is used to change the molecules from liquid to gas? if thats what your asking.

Explanation:

COLLEGE

Consider two solutions, solution A and solution B. [H+] in solution A is 500 times greater than that in solution B. what is the difference in the pH values of the two solutions?

Answers

The difference in the pH values of the two solutions is 2.7

Let the [H+] of solution B be 0.0001 M

Thus,

The [H+] of solution A = 0.0001 × 500 = 0.05 M

  • Next, we shall determine the pH of each solution

For solution A:

Hydrogen ion concentration [H+] = 0.0001 M

pH =?

pH = –Log [H+]

pH = –Log 0.0001

pH = 1.3

For solution B:

Hydrogen ion concentration [H+] = 0.05 M

pH =?

pH = –Log [H+]

pH = –Log 0.05

pH = 4

  • Finally, we shall determine the difference in the pH values of the two solutions

pH of solution A = 1.3

pH of solution B = 4

Difference =?

Difference = 4 – 1.3

Difference = 2.7

Therefore, the difference in the pH values of the two solutions is 2.7

Learn more: brainly.com/question/9278932

Answer: The difference in the pH values of the two solutions is 2.7

Explanation:

pH or pOH is the measure of acidity or alkalinity of a solution.

pH is calculated by taking negative logarithm of hydrogen ion concentration.

a) For solution A, let  =

Putting in the values:

b) For solution B,  =

Putting in the values:

Thus the difference in pH will be (4-1.3)= 2.7.

MIDDLE SCHOOL

Provide three ways that humans have had a impact on the greenhouse effect on Earth? Describe how the activity has had an impact on the greenhouse effect.

Answers

Burning of fossil fuels, increase use of vehicles and use of household appliances like refrigerator are the three ways humans have had an impact on the greenhouse effect on Earth

Explanation:

  • Burning of fossil fuels for industrial purpose cause the emission of greenhouse gases such as Chlorofluorocarbons (CFCs), Carbon dioxide, methane and nitrous oxide.
  • The smoke comes from the vehicles contain carbon dioxide which increases the number of greenhouse gases in the atmosphere .
  • Use of household appliances will also lead to the emission of greenhouses gases mainly, CFCs (Chlorofluorocarbons) .
  • Increase in the number of greenhouse gases in the atmosphere will lead to climate change.

HIGH SCHOOL

Is a compound containing carbons, hydrogens, and hydroxyl groups (oh) that serves as the "backbone" for various lipids?

Answers

Answer is: glycerol.
Glycerol (1,2,3-Propanetriol, glycerine or glycerin) is a simple polyol compound with formula (OH-CH₂-CH(OH)-CH₂OH or C₃H₈O₃). The glycerine backbone is found in all lipids known as triglycerides (ester derived from glycerol and three fatty acids). Glycerol is soluble in water hygroscopic.
MIDDLE SCHOOL

The nobel prize winner Italian scientist who pioneered nuclear reactions was

Answers

Enrico Fermi was the Italian scientist won the nobel prize.
COLLEGE

12. The vapor pressure of water at 90°C is 0.692 atm. What is the vapor pressure (in atm) of a solution made by dissolving 3.68 mole(s) of CsF(s) in 1.00 kg of water? Assume that Raoult's law applies.

Answers

Answer : The vapor pressure (in atm) of a solution is, 0.679 atm

Explanation : Given,

Mass of = 1.00 kg = 1000 g

Moles of = 3.68 mole

Molar mass of = 18 g/mole

Vapor pressure of water = 0.692 atm

First we have to calculate the moles of .

Now we have to calculate the mole fraction of

Now we have to partial pressure of solution.

According to the Raoult's law,

where,

= vapor pressure of solution

= vapor pressure of water = 0.692 atm

= mole fraction of water = 0.938

Therefore, the vapor pressure (in atm) of a solution is, 0.679 atm

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