7. (a) Using two examples, explain how covalent compounds are formed. [4 marks]
(b) State three physical properties of covalent compounds. [3 marks]
(c) Describe an experiment how you can carry out an experiment to investigate one of the properties mentioned above. [3 marks]

8. (a) Using two examples, explain how covalent compounds are formed. [14 marks]
(b) State three physical properties of covalent compounds.[3 marks]
Describe an experiment how you can carry out an experiment to investigate one of the properties mentioned above. [3 marks]​

When the hematite particles rearrange to form a new substance", this statement describes chemical change.

A chemical change is a change of materials into another, new materials with different properties and one or more than one new substances are formed.

As a chemical changes is usually a change where a substance undergoes a chemical change and forms a new substance; which cannot be easily reversed into reactants by any simple physical methods.

In this example the hematite ore forms a new substance by an irreversible chemical change.

Hence, "The hematite particles rearrange to form a new substance", this statement describes chemical change.

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Answer:

6.40 is the answer to your question

The number of moles of oxygen in 1.60 moles of sodium hydrogen phosphate is 6.4 moles

Let's represent the chemical formula of the compound. The chemical formula of sodium hydrogen phosphate is as follows:

The chemical formula of a compound is a symbolic expression use to signify the number of atoms present in a molecular substance. Therefore,

sodium hydrogen phosphate  = Na₃PO₄

Therefore,

1 mole of Na₃PO₄ = 4 moles of oxygen

1.60 moles of Na₃PO₄  = ? moles of oxygen

cross multiply

number of moles of oxygen = 1.60 × 4

number of moles of oxygen = 6.4 moles

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Temperature change

Answer:

NO. 10.

performed experiments

NO. 11.

Inference

Explanation:

No 10.

in order to prove that Mary Mellon was in fact infected by typhoid proper experiments needs to be carried out.

No. 11

inference means an assumption due to the situation.

Answer:

2Na + 2H2O → 2NaOH + H2

Explanation:

This is the balanced equation of,

Sodium + water → sodium hydroxide + hydrogen

Fluorine (F) and iodine(I) are the halogen elements that belong to group 17. They differ from each other as fluorine has 3 fewer energy shells than iodine. Thus, option D is correct.

Halogen is a nonmetallic element that belongs to group 17 and consists of six elements namely fluorine, bromine, tennessine, chlorine, astatine, and iodine.

They are diatomic and have 7 valence electrons in the outer shell, which makes them highly reactive and electronegative. The shielding effect is less in F than I due to the closer placement and attraction of the valence electron to the nucleus.

Fluorine differs from iodine as it has a smaller size with fewer energy shells than iodine. Iodine has five energy shells,  whereas fluorine has two energy shells that make the difference of three shells between them.

Therefore, F and I differ from each other.

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Answer:

Thus, the element containing the greatest number of atoms is 12 g He. Thus, the correct option is (4) 12 g He. Note: The number of atoms of a compound is Avogadro's number for 1 mole of compound. The number 6.022×1023 is known as Avogadro's number.

Explanation:

(4)✔️ 12 g He

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Answer:

120gram I think so this is the answer if the answer is correct plz mark me as brainliest.

Answer:

valence

Explanation:

the level of energy electrons have within a general shape the energy level is valence.

19. place moth balls in the closet and observe after several days.

20. whenever wax or a candle burns it turns from solid to liquid but again at room temperature it turns to solid

21. evaporation, condensation, precipitation

22. it produces new substances

23. vinegar Bubbles when baking soda is added

24. steam

Answer:

His total displacement is 80 m northwards

Explanation:

Given;

Mike's first displacement, x₁ = 100 m North

Mike's second displacement, x₂ = 30 m South

Mike's third displacement, x₃ = 10 m North

Let his Northwards direction be positive, and

his Southwards direction be negative

His total displacement = (100 m North) + ( - 30 m South) + (10 m north)

                                     = (100 m + 10m - 30 m)

                                     = 80 m  Northwards

Answer:

thnx for the points too muchee

Explanation:

Answer:

Explanation:

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Answer:

Answer:

Explanation:

Overuse of antibiotics leads to bacteria's resistance against our drugs. This is increasing at an alarming rate and the reason is that overuse of antibiotics kills bacteria that lack the "resistance" gene or gene that can help them survive the antibiotics (similar is the case for insects that die to insecticides). But, some bacteria can have random mutations in their gene that can help them survive the antibiotic (similar is the case for some insects that can survive the insecticide), thus the surviving bacteria give rise to next generation of bacteria that are resistant to the given antibiotic (similar to how insects that survive the insecticide give birth to new insects that are resistant to insecticide too). Soon, every generation adds new antibiotic resistant bacteria (or new insecticide resistant insects in the case of insects) which is dangerous for all of life on this planet. Therefore, both are similar in the sense that new generations of these organisms will be resistant to our weapons against them.

Answer:

The magnetic field of an atom, say H (one electron revolving around a proton) is composed of two separate contributions: an orbital magnetic moment and a spin magnetic moment. We get magnetic moments because of electromagnetic induction associated with each type of electron motion. The electron revolving around the proton with a certain angular momentum is related to the associated orbital magnetic moment (and, yes, we model it as a wire loop with current expressed in terms of the orbital velocity). This can be calculated using elementary mechanics. The spin magnetic moment is a little trickier because it is caused by the intrinsic spin of the electron which is a quantum phenomenon; therefore, this spin magnetic moment can only be calculated using quantum mechanics. In the end, we get a certain net magnetic moment associated with this motion of the electron in an atom. It is important to notice that this atom acts as a magnetic dipole (remember, as of yet, magnetic monopoles don't exist!).

If we take a bulk magnet like you might have on your fridge, it would be composed of atoms. Each atom operates as a magnetic dipole, but due to internal atomic structures, the atoms actually align themselves into separate magnetic domains, each with a net magnetic moment (caused my individually adding up those atomic dipole moments). In a common magnet (ferromagnet), these domains all point the same direction and stay that way, creating a permanent bulk magnetic dipole.

So in a way, there is no difference between the magnetic field of an atom and that of a magnet because one is simply a sum of the other, making both magnetic dipoles. Of course, here we see that there's nothing that fundamental about the magnetic force. In reality, the magnetic force is a relativistic effect caused by the movement of a charged particle, making electricity (i.e. charge) the underlying property at work here. Electromagnetic induction is really a shortcut to understand the magnetic force without worrying about relativistic mechanics. If we were to discover magnetic monopoles (i.e. "magnetic" charge), this would re-write a lot that we know about electromagnetism because we couldn't label all magnetic forces as by-products of moving electric charge

Answer:

The chloroplasts form a spiral around the vacuole and have specialized bodies known as pyrenoids that store starch. The cell wall consists of an inner layer of cellulose and an outer layer of pectin, which is responsible for the slippery texture of the algae.

Explanation:

hope it is helpful to you

Answer:

Isotope 2

Explanation:

Isotope 2 is the most abundant. Its percent abundance is 78.68% which is the largest percentage, and therefore the most common of the isotopes presented.

Good luck!

Both have Giant Covalent Structures, resulting in very high melting temperatures. However each carbon atom in Diamond has 4 covalent bonds with other Carbons, making it extremely strong and hard. On the other hand, each carbon in graphite is bonded to three carbons, and therefore graphite is formed in layers.

Answer: The correct option is C ( is very hard and burns cleanly).

Explanation:

COAL is a form of rock that is made up of mostly carbon amongst other elements which includes sulphur, nitrogen, hydrogen and oxygen. There are different types of coal which include:

--> anthracite ( 90% carbon)

--> bituminous coal ( 70-90% carbon)

--> lignite ( 60- 70% carbon) and

--> peat (60 % carbon).

Anthracite is the type of coal that contains the highest carbon content ( 90% carbon). This makes it very hard and is often a times referred to as HARD COAL. Anthracite is a higher quality coal for domestic and open fire heating. This is because it contains less impurities than other type of coal and thereby making it to BURN CLEANLY avoiding atmospheric pollution.

Answer:

Cr(NO3)3 (aq) +K3PO4 (s)

Explanation:

Answer:

Z negative

Explanation:

The negative charge shows that this is an electron. Electrons are present outside the nucleus of the atom and having negative charge. Usually represented by e-

Answer:

Only Z?

Explanation:

Answer:

8.87 × 10³ moles.

Explanation:

To convert number of molecules of sulfur hexafluoride (SF6) to moles (n), we divide by Avogadro's number (6.02 × 10²³)

That is; n = N ÷ nA

According to the question, 5.34 x 10^27 molecules of SF6 was given in this question. Hence, the number of moles it contains is given as:

n = 5.34 x 10^27 ÷ 6.02 × 10²³

n = 5.34/6.02 × 10^ (27-23)

n = 0.887 × 10⁴

n = 8.87 × 10³ moles.

Answer:

a group of electrochemical cells that can be recharged

Answer: A hygroscopic substance is one that readily attracts water from its surroundings, through either absorption or adsorption

Explanation:

Answer:

Pb(NO₃)₂ + Na₂CrO₄ —> PbCrO₄ + 2NaNO₃

The coefficients are: 1, 1, 1, 2

Explanation:

Pb(NO₃)₂ + Na₂CrO₄ —> PbCrO₄ + NaNO₃

The above equation can be balance as follow:

Pb(NO₃)₂ + Na₂CrO₄ —> PbCrO₄ + NaNO₃

There are 2 atoms of Na on the left side and 1 atom on the right side. It can be balance by writing 2 before NaNO₃ as shown below:

Pb(NO₃)₂ + Na₂CrO₄ —> PbCrO₄ + 2NaNO₃

Now the equation is balanced.

The coefficients are: 1, 1, 1, 2

Answer:

39.02amu

Explanation:

According to this question, there are four (4) isotopes for element X with the following relative abundance:

Isotope 1 = 9.67%, mass no: 38

Isotope 2 = 78.68%, mass no: 39

Isotope 3 = 11.34%, mass no: 40

Isotope 4 = 0.31%, mass no: 41

To find the average atomic mass of element X, we multiply each isotopes' relative abundance by its mass no and find the sum as follows:

We convert each percentage to decimal abundance:

Isotope 1 = 9.67% = 0.0967

Isotope 2 = 78.68% = 0.7868

Isotope 3 = 11.34% = 0.1134

Isotope 4 = 0.31% = 0.0031

(0.0967 × 38) + (0.7868 × 39) + (0.1134 × 40) + (0.0031 × 41)

3.6746 + 30.6852 + 4.536 + 0.1271

Average atomic mass = 39.02amu

m=y2 −y1/x2-x1

Explanation:

3-5/2-12=1/5

Answer:

Unicellular organisms consist of only one cell and multicellular organisms consist of many cell.

Explanation:

Living things made up of a cell are called unicellular beings. They are very small and simple. In other words, unicellular organisms are those that are formed only by a single cell in which all the vital functions necessary for life are produced. For this reason, they are mostly microscopic organisms. Examples of unicellular organisms are viruses or bacteria.

Multicellular organisms are made up of a large number of cells. They present, therefore, a greater complexity than unicellular organisms in terms of the functions they develop. All current multicellular organisms come from a single cell, that is, they begin their life being unicellular. That is, they are formed from a zygote. Some examples of multicellular organisms are mammals, fungi, and mosses.

So, unicellular organisms consist of only one cell and multicellular organisms consist of many cell.