1. Lithium, water, edible salt, chalk, Carbon, Lime, Nitrogen, Potassium, Oxygen,
Iodides, Iron, Chlorine, etc are some matters.

(a) Expressing the matters of the stem by symbol and formula separate the elements
and compounds. ---3 marks

Answers

Answer 1

Answer:

Explanation:

An atom is the smallest unit of an element that can take part in a chemical reaction. Atoms (and there corresponding symbols) mentioned in the question are

Lithium ⇒ Li

Carbon ⇒ C

Nitrogen ⇒ N

Potassium ⇒ K

Oxygen ⇒ O

Iron ⇒ Fe

Chlorine ⇒ Cl

A compound is substance that contains two or more atoms that are chemically combined and can be represented with a chemical formula. The compounds (and there corresponding formula) mentioned in the question are

Water ⇒ H₂O

Edible salt (sodium chloride) ⇒ NaCl

Chalk (calcium carbonate) ⇒ CaCO₃

Lime (calcium oxide) ⇒ CaO

Iodides (such as sodium iodide and potassium iodide) ⇒ NaI and KI respectively


Related Questions

A solution has a pH of 2. Which best describes the solution? A strong acid, a strong base, a neutral solution, a weak base

Answers

Answer:

The best solution is Strong acid

Explanation:

add me on snap Andy142512

A solution that has a pH of 2 is a strong acid solution.

Explanation:

The pH of the solution is defined as the negative logarithm of the hydrogen ions concentration in an aqueous solution.

                            [tex]pH=-\log[H^+][/tex]

If the pH of the solution is less than 7 is said to be an acidic solution.If the pH of the solution is equal to 7 is said to be a neutral solution.If the pH of the solution is greater than 7 is said to be an alkaline solution.

So, from this, we can conclude that solution with a pH of 2 which is less than 7, hence strong acidic solution.

Learn more about the pH of the solution here:

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baking soda and vinegar lab demo part 2 mass! 7th grade please help!

Answers

Answer:

just watch the video, what does it start with, write that down for each trial, then what does it end with, then starting mass - ending mass is the change mass

GIVING BRAINLY
this equation describes a chemical reaction : aluminum + iron oxide → aluminum oxide + iron
Which of the following statements about the chemical equation is true? * view attachment for answer choices*

Answers

Answer:

C. Iron oxide is a mixture of iron and oxygen

When water is solid, do molecules move?

Answers

Answer:

Ice is water in its solid form. Ice keeps its shape, even if it's removed from the container. The molecules in ice are locked into place and cannot move or slide past one another, but they do vibrate a little bit.

Explanation:

As the temperature drops or decreases, the water molecules gradually slow down. Eventually they stop moving and simply vibrate back and forth. At this point ice is formed, the solid phase of water. If the temperature is allowed to increase, the molecules will once again begin to vibrate faster and faster.

Answer:Ice is water in its solid form. Ice keeps its shape, even if it's removed from the container. The molecules in ice are locked into place and cannot move or slide past one another, but they do vibrate a little bit.

Explanation:

Mark & Sally were in lab and they were working on a chemical reactions experiment. They mixed 2 liquids together and a white sold color appeared. What can Mark & Sally conclude as their observation?

A chemical change
B physical change

Answers

Answer:

A chemical change

Explanation:

From the observation, a chemical change has ensued.

A chemical change is one in which new kind of matter is formed. It is always accompanied by energy changes . This process is not easily reversible.

This process depicted by Mark and Sally is chemical change. This reaction is a precipitation reaction since an insoluble solid has been formed. In chemical changes the process is not reversible.

When heated, calcium carbonate decomposes according to the equation given below:

CaCO3 --> CaO + CO2
If 50.0 g of CaCO3 react but only 20.0 g of CO2 are recovered, what is the percent yield of this reaction?


90.9%
40.0%
66.7%
250%

Answers

Answer:

Percent yield = 90.9%

Explanation:

Given data:

Mass of CaCO₃ = 50.0 g

Mass of CO₂ produced = 20.0 g

Percent yield = ?

Solution:

Chemical equation:

CaCO₃ →  CaO + CO₂

Number of moles of CaCO₃:

Number of moles = mass/molar mass

Number of moles = 50.0 g/ 100.1 g/mol

Number of moles = 0.5 mol

Now we will compare the moles of CO₂ with CaCO₃.

                      CaCO₃          :        CO₂

                          1                :           1

                       0.5               :          0.5

Mass of CO₂: Theoretical yield

Mass = number of moles × molar mass

Mass = 0.5 mol × 44 g/mol

Mass = 22 g

Percent yield:

Percent yield = ( actual yield / theoretical yield ) × 100

Percent yield = (20.0 g/ 22.0 g) × 100

Percent yield = 0.909 × 100

Percent yield = 90.9%

A 2.0 sample of N2 occupy 50.0L at 15 degrees Celsius and 640mmHg. What volume will the gas occupy at 45 degrees Celsius and 160mmHg?

Answers

Answer:

220.8L

Explanation:

Given parameters:

Initial volume  = 50L

Initial temperature = 15°C  = 288K

Initial pressure = 640mmHg

Final temperature  = 45°C  = 318K

Final pressure  = 160mmHg

Unknown:

Final volume  = ?

Solution:

Using the combined law;

        [tex]\frac{p_{1}v_{1} }{T_{1} }[/tex]  = [tex]\frac{p_{2}v_{2} }{T_{2} }[/tex]  

p,v and T are pressure, volume and Temperature

    [tex]\frac{640 x 50}{288}[/tex]  = [tex]\frac{160 x v_{2} }{318}[/tex]

     160 x 288 x v₂ = 640 x 50 x 318

                         v₂ = 220.8L

How do mammals protect their young?

Answers

Answer:

Explanation:

Baby pigs, dolphins, bats and elephants all drink milk! Because the babies rely on their mother's milk to live, the mammal mommies have to care for their young. ... Through copying their mothers, baby mammals learn everything they need to survive

Answer:

by be young

Explanation:

wow just use you brain

2CO2 + 3H2O + 4Br2

C =

O =

H =

Br =

Answers

Explanation:

2CO2 + 3H2O + 4Br2

C = 2

O = 5

H = 6

Br =8

High percent yield generally indicates a carefully run experiment.
O True
False

Answers

in my opinion it's true!!!

A cylinder at left with balls evenly spaced throughout the cylinder with an arrow leading to a cylinder at right with balls stacked near the bottom of the cylinder.
Which change of state is shown in the model?

condensation
deposition
boiling
freezing

Answers

Answer:

condensation

Explanation:

The state of change shown in the diagram is a condensation process. During condensation, heat is removed from vapor or gases and then they aggregate back to the liquid state.

The image to the left is that of a typical gas molecule. To the right we have a liquid where the particles have aggregated In going from a gas to liquid, the phase change is a condensation reaction. This is a form of physical change.

Answer:

Use these images to identify each state of matter.

A cylinder at left labeled A contains balls widely separated in space. A cylinder in the center labeled B contains balls stacked near the bottom of the cylinder. A cylinder at right labeled C contains balls in a layer along the bottom of the cylinder.

Match each image with the correct state of matter.

 

A:  

gas

B:  

solid

C:  

liquid

Explanation: i got it right trust me

In the reaction 2Li(s) + 2H2O(I) -> 2LiOH(aq) + H2(g), which compound is in the aqueous state?

A. Li

B. H2O

C. LiOH

B. H2

Answers

The substance that is in aqueous state in the reaction is LiOH from the equation shown.

What is an aqueous state?

An aqueous state is a state in which a substance is dissolved in water. This implies that the substance is in solution.

Thus, the substance that is in aqueous state in the reaction is LiOH from the equation shown.

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Answer:

C

Explanation:

What is a scientific model? How is a scientific model helpful to the brain for relaying a scientific
concept?

Answers

Answer: A scientific model is a physical and mathematical and conceptual representation of a system of ideas, events or processes.

ANd also for your second question i dont know what you mean?

Explanation:

Scientists work to recognize and comprehend patterns in our world by applying their scientific expertise to provide predictions about the patterns.

What is the main purpose of scientific model?

In a range of scientific specialties, from chemistry and physics to biology and the Earth sciences, research models are employed to explain and forecast the behavior of real things or systems. The ability to depict things that are too little or enormous, explain either past or present, and forecast the future are all advantages of employing model beyond nature.

Why are scientific models important?

Models can help you visualize something is difficult to see or understand. Models can help in scientific predictions, process comprehension, and concept communication. Because it frequently includes a variety of hypotheses or facts, an evolutionary theory varies from other general explanations. A science simulation may be used to verify a scientific theory or to demonstrate a scientific model.

To know more about Scientific model visit:

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what is the gel-like part of the eye?

Answers

Answer:

vitreous

Explination:

The vitreous is the gel-like fluid that fills your eye. It's full of tiny fibers that attach to your retina (the light-sensitive layer of tissue at the back of the eye). As you get older, the fibers of your vitreous pull away from the retina.

Answer:

The vitreous

Explanation:

Out of magnesium, iron, calcium, mercury, copper, or aluminum which metal would be the most useful when transporting acids or water solutions? PLEASE HELP!!! Thank you

Answers

May be mercury is the best choice because it would not react with acid

Will give 50 points, If a decrease in temperature accompanies a reaction, what occurred?


Energy was released.


Energy was destroyed.


Energy was created.


Energy was absorbed.

Answers

Answer:

A.

Explanation:

Answer: Energy is Being absorbed

A sample of 5.0 g of hydrogen gas reacts with 5.0 g of oxygen gas.
2H2(g) + O2(g) > 2H2O

Please answer the questions in a b c d and e, or at least in any of the ones you know. Thank you.

Answers

The percent yield of the reaction has been 74.47%.

The balanced chemical equation for the reaction has been:

[tex]\rm 2\;H_2\;+\;O_2\;\rightarrow\;2\;H_2O[/tex]

(a) The theoretical yield can be calculated as:

The theoretical yield of water has been:

1 mole of oxygen produces = 2 moles of water

0.1562 moles of oxygen produces = 0.1562 [tex]\times[/tex] 2

= 0.312 moles of water.

The mass of water has been = moles [tex]\times[/tex] molecular weight

The theoretical yield of water = 0.312 [tex]\times[/tex] 18 grams

The theoretical yield of water = 5.616 grams.

(b) The limiting reactant has been the one whose concentration has been in a lesser quantity for the complete utilization of other reactants.

According to the reaction, for the complete utilization of 2 moles of Hydrogen, 1 mole of oxygen has been used.

The moles of 5 grams Hydrogen:

Moles = [tex]\rm \dfrac{weight}{molecular\;weight}[/tex]

Moles of hydrogen = [tex]\rm \dfrac{5}{1}[/tex]

Moles of hydrogen = 5 mol.

Moles of Oxygen = [tex]\rm \dfrac{5}{32}[/tex]

Moles of oxygen = 0.1562 mol.

For the complete utilization of 5 moles of hydrogen 2.5 moles of oxygen has been required.

Since the oxygen has been present in a lesser quantity, the oxygen has been the limiting reactant.

(c) The consumption of 0.1562 moles of Oxygen has required 0.312 mol of Hydrogen. The hydrogen has been present in a higher quantity than required.

Thus. hydrogen has been the excess reactant.

(d) The remained excess reactant has been:

Remained = Total - consumed

Remained = 5 - 0.312

Remained = 4.68 mol.

The excess reactant has been 4.68 mol extra than required.

(e) The theoretical yield of water has been:

1 mole of oxygen produces = 2 moles of water

0.1562 moles of oxygen produces = 0.1562 [tex]\times[/tex] 2

= 0.312 moles of water.

The mass of water has been = moles [tex]\times[/tex] molecular weight

The theoretical yield of water = 0.312 [tex]\times[/tex] 18 grams

The theoretical yield of water = 5.616 grams.

The actual yield of water has been 4.2 grams.

The percent yield of water = [tex]\rm \dfrac{Actual\;yield}{Theoretical\;yield}\;\times\;100[/tex]

The percent yield of water = [tex]\rm \dfrac{4.2}{5.616}\;\times\;100[/tex]

The percent yield of water = 74.74 %

For more information about the limiting reactant, refer to the link:

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Answer:

a- 5.616

b- Oxygen

c- hydrogen

d- 4.68 extra

e- 74.47%

I hope this helps! Cheers ^^

Need Help ASAP
Calculate the pH of:

a) 0.1 M HF Ka = 7.2 x 10-4

b) 1 x 10-3 M HNO3

c) 1 x 10-8 M HCl

Answers

a. pH=2.07

b. pH=3

c. pH=8

Further explanation

pH=-log [H⁺]

a) 0.1 M HF Ka = 7.2 x 10⁻⁴

HF= weak acid

[tex]\tt [H^+]=\sqrt{Ka.M}\\\\(H^+]=\sqrt{7.2.10^{-4}\times 0.1}\\\\(H^+]=8.5\times 10^{-3}\\\\pH=3-log~8.5=2.07[/tex]

b) 1 x 10⁻³ M HNO₃

HNO₃ = strong acid

[tex]\tt pH=-log[1\times 10^{-3}]=3[/tex]

c) 1 x 10⁻⁸ M HCl

[tex]\tt pH=-log[1\times 10^{-8}]=8[/tex]

Metal oxides are in which state?

Answers

Answer:

Metal oxides are crystalline solids that contain a metal cation and an oxide anion. They typically react with water to form bases or with acids to form salts.

Explanation:

Hope this helps!

Make the following conversion.

60 dkm = _____ km

6,000
0.060
60,000
0.60

Answers

Answer:

0.6

Explanation:

the _ lobe is important in processing visual information.

a. parietal
b. frontal
c. temporal
d. occipital

Answers

Answer:

It's D

Explanation:

In order for photosynthesis to take place, energy in the form of ______ is required.

A. Sound

B. Light

C. Electricity

D. Kinetic

Answers

B. Light
Chloroplasts on leaves absorb the sunlight to make energy which is what causes photosynthesis. Hope this helps!

HELP!!

H2SO4 is _____.

a base
an acid
a neutral

(The 2 is small and so is 4)

Answers

Answer:

Acid

Explanation:

acid

Answer:

An acid

Explanation:

H2OSO4 is Sulfuric Acid

Which is equal to a temperature of 50 degrees F? 18 degrees C, 46 degrees C, 10 degrees C, 32 degrees C?

Answers

Answer:

10 degrees C

Explanation:

1. Which of the following is NOT a main tissue type? *

Answers

Answer:

there is nothing follow that

Explanation:

Melting chocolate (a change of state) is an example of a

Answers

It is an example of a physical change because the chocolate changes from a solid to a liquid however it’s chemical composition is not changed so it’s a physical change.

Compare the elements: Sn, Sb, Te, and I:
Which has the lowest ionization energy?
Why?

Answers

Answer:

Sn

Explanation:

Tin, Sn, will have the lowest ionization energy from the given choices.

  Sn is an element is the fourth group on the periodic table.

Ionization energy is a measure of the readiness of an atom to lose an electron. The lower the value, the easier it is for an atom to want to lose an electron and vice versa.

Across a period, I.E increases progressively from left to right due to the decreasing atomic radii caused by the increasing nuclear charge which is not compensated for by successive electronic shells.

       Sn, Sb, Te and I are all in the 5th period.

In an experiment, the gram atomic mass of magnesium was determined to be 14.7. Compared to the accepted value of 24.3, the percent error for this determination was
39.5
1.65
24.7
98.4

Answers

Answer:

The answer is 39.5 %

Explanation:

The percentage error of a certain measurement can be found by using the formula

[tex]P(\%) = \frac{error}{actual \: \: number} \times 100\% \\[/tex]

actual mass = 24.3

error = 24.3 - 14.7 = 9.6

We have

[tex]p(\%) = \frac{9.6}{24.3} \times 100 \\ = 39.506172839...[/tex]

We have the final answer as

39.5 %

Hope this helps you

1.How far can you travel if you drive 4 hours and can average 120 Km/hr?
a.30 Km
b.480 Km
c.80 Km

Answers

Answer:

B

Explanation:

D=S×T

=120km/h×4hrs

=480km

Answer:

the answer is b

Explanation:

this is the answer :)

Is this true Bc I’m not sure

Answers

Answer:

????? questions there no question

Answer:

what

Explanation:

Other Questions
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