The diagram below represents changes in the types of plants growing in the same area during four different time periods. Different types of plants
have been labeled for each time period.oo
Hardwood trees
Softwood trees
Small plants and
shrubs
Grasses
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Time
This change in plant types over time is an example of

Answer:

i good at chemistry

Explanation:

not all but i try

Answer:

Ionic bond and covalent bond

Explanation:

The two main types of chemical bonding are ionic bond and covalent bond.

In an ionic bond, there is a transfer of electrons from one atom to another. Usually from a metal to a nonmetal leading to the existence of an ion pair. Ionic compounds are soluble in water and have high melting and boiling points due to the strong electrostatic interaction between ions in the compound.

A covalent bond involves sharing of electrons between atoms. In an ordinary covalent bond, the shared electrons are furnished by the two bonding atoms while in a dative covalent bond, the two bonding electrons are furnished by only one of the bonding species.

Answer:

As we know that alkalis react with oil to form soap. As our skin contains oil so when we touch strong alkalis, a reaction takes place and the soapy solution is formed. Hence we should wear gloves.

Answer:

As we know that alkalis react with oil to form soap. As our skin contains oil so when we touch strong alkalis, a reaction takes place and the soapy solution is formed. Hence we should wear gloves.

Explanation:

it from internet

Answer:

A

Explanation:

because it can share and remain with ither electrons

Answer:

B. CH3COOH and NaCH3COO

Explanation:

CH3COOH and NaCH3COO will make a buffer when mixed.

Buffer solutions resist a change in pH when small amounts of a strong acid or a strong base are added. A solution of acetic acid and sodium acetate CH3COOH + CH3COONa is an example of a buffer that consists of a weak acid and its salt.

Buffers are broadly divided into two types – acidic and alkaline buffer solutions. Acidic buffers are solutions that have a pH below 7 and contain a weak acid and one of its salts. For example, a mixture of acetic acid and sodium acetate acts as a buffer solution with a pH of about 4.75.

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Answer: The given type of chemical reaction is a double replacement reaction, and each compound has the same set of ions.

Explanation:

When two different compounds chemically react with each other and their ions get exchanged with each other then it leads to the formation of two new compounds. This type of reaction is called double displacement reaction.

For example, [tex]KBr + AgNO_{3} \rightarrow KNO_{3} + AgBr(\downarrow)[/tex]

Here, both KBr and [tex]AgNO_{3}[/tex] are ionic compounds that leads to the formation of two new ionic compounds which are [tex]KNO_{3}[/tex] and AgBr.

Thus, we can conclude that the given type of chemical reaction is a double replacement reaction, and each compound has the same set of ions.

Answer:

the answer is half arrow

Reactivity of non-metals depend on their ability to gain electrons. So, smaller is the size of a non-metal more readily it will attract electrons because then nucleus will be more closer to valence shell. ... Hence, Br is the non-metal which will be more reactive than At.

Answer:

br is more reactive than as

Answer:

0.32M

Explanation:

Using the following formula;

CaVa = CbVb

Where;

Ca = concentration of acid (M)

Cb = concentration of bass (M)

Va = volume of acid (HCl)

Vb = volume of base (NaOH)

According to this question, the following were given:

Ca = ?

Cb = 2M

Va = 1.824L

Vb = 0.294L

Using CaVa = CbVb

Ca × 1.824 = 0.294 × 2

1.824Ca = 0.588

Ca = 0.588 ÷ 1.824

Ca = 0.32M

Answer:

1.3 M

Explanation:

1 mole= Concentration * Volume

1 mole=C*0.75 L

C=1.3 M

Answer:

The periodic table

Explanation:

I'm not really sure what your question is. . . I'm assuming this is what you're looking for

Answer:

Total ionic equation = Ni²⁺ + 2Cl⁻¹ + 2Na⁺ + CO₃⁻² → 2Na⁺ + 2Cl⁻¹ + NiCO₃ (s)

Net ionic equation = Ni²⁺ + CO₃⁻² → NiCO₃ (s)

NiCl₂ (aq) + Na₂CO₃ (aq) → 2NaCl (aq) + NiCO₃ (s)

First, we'll need to expand the complete chemical equation into a total ionic equation (to determine whether a chemical is aqueous or solid, use a solubility chart until the rules are memorized).

Ni²⁺ + 2Cl⁻¹ + 2Na⁺ + CO₃⁻² → 2Na⁺ + 2Cl⁻¹ + NiCO₃ (s)

Now, using the total ionic equation, we can find the net ionic equation. In order to do this, we need to cancel out the aqueous solutions that don't form into solids, as they are extraneous.

Ni²⁺ + 2Cl⁻¹ + 2Na⁺ + CO₃⁻² → 2Na⁺ + 2Cl⁻¹ + NiCO₃ (s)

Ni²⁺ + CO₃⁻² → NiCO₃ (s)

I hope this helped!

Answer:

last option is correct.

Air molecules surrounding the metal will speed up and metal molecules will slow down

Explanation:

the metal cools when placed in room temperature air which causes surrounding air to heat up.

the speed of molecules slow down for any material which cools and molecules speed increases when any material heats up

Answer:

2Al(NO3)3+3K2CO3->Al2(CO3)3+6KNO3

So the right answer is 2,3,1,6

Explanation:

First you look at the equation that isn't balance, you can see Al(NO3)3 while Al2(CO3)3, so you put 2 in Al(NO3)3.

Now we have 2Al is correct, but 6NO3. So we have 6KNO3, it also means we have 6K

Finally, we only have 2K as K2CO3 so we put 3 in it, so we have 3K2CO3.

Sorry about my explanation, it's hard to understand but the answer is correct.

mass of 1 mole of N is 14g

so mass of 3.45 mole is

3.45 × 14 = 48.3 g

Answer:

See explanation

Explanation:

pOH = -log[OH^-]

pOH =-log[1×10^-4 molL-1]

pOH = 4

pH +pOH =14

pH = 14 -4

pH =11

b) pOH = -log[OH^-]

pOH =-log[4.9×10^-2molL-1]

pOH = 1.31

pH +pOH =14

pH = 14 -1.31

pH =12.69

c)

pH= -log[H^+]

[H^+] = Antilog [-pH]

[H^+] = Antilog [-3]

[H^+] = 1 × 10^-3 molL-1

d) pOH = -log[OH^-]

[OH^-] = Antilog[-pOH]

[OH^-] = Antilog[-10.4]

[OH^-] = 3.98 ×10^-11

[OH^-] [H^+] = 1 × 10^-14

[H^+] = 1 × 10^-14/3.98 ×10^-11

[H^+] =2.5 ×10^-4 MolL^-1

e) A solution of pH 9 is basic because the pH scale is calibrated in such as way that 0-6.9 is acidic, 7 is neutral and 8 - 14 is basic.

f)

[H^+] = number of moles/volume

[H^+] = 0.35 moles/8L

[H^+] = 0.044 MolL^-1

pH = - log [H^+]

pH = -log [0.044 MolL^-1]

pH= 1.36

Answer:

0.13 molL-1

Explanation:

We must first obtain the number of moles of sodium carbonate as follows;

Number of moles = mass/molar mass

Number of moles = 21.2 g/106 g/mol

Number of moles= 0.2 moles

Number of moles = concentration × volume

Volume = 1.50 L

Concentration = number of moles/volume

Concentration = 0.2 moles/1.5 L

Concentration = 0.13 molL-1

Answer: London dispersion forces of molecular attraction is the weakest.

Explanation:

The forces which exist between neighboring atoms, molecules or ions can be force of attraction or force of repulsion. These forces are called intermolecular forces.  

When ions with same charge come in contact with each other then force of repulsion is there but when ions with opposite charge comes in contact with each other then force of attraction will be there.

These forces are described as follows.

London dispersion forces: The electrostatic attraction between atoms or molecules causes a temporary induced charge on the respective atoms. These attractive forces are weak in nature and called London dispersion forces.

Hydrogen bond: When a hydrogen atom is attached to electronegative atom like fluorine, nitrogen and oxygen then bonding between these atoms is called a hydrogen bond.

Dipole-dipole interaction: When positive end of one polar molecule gets attracted by the negative end of another polar molecule then force existing between these ends is called dipole-dipole interaction.

Single covalent bond: When an atom is sharing its valence electrons with another atom then it is called a covalent bond.

Thus, we can conclude that London dispersion forces of molecular attraction is the weakest.

Answer:

Always equal to the total moles of the products.

Explanation:

The law of conservation of mass states that mass in an isolated system is neither created nor destroyed by chemical reactions or physical transformations. According to the law of conservation of mass, the mass of the products in a chemical reaction equal to the mass of the reactants.

Answer:

Lithium perchlorate

Explanation:

The compound formed from lithium chloride and oxygen is lithium oxide (Li₂O).

When lithium chloride (LiCl) reacts with oxygen (O₂), they combine to form lithium oxide (Li₂O). In this reaction, each lithium-ion (Li⁺) from lithium chloride combines with an oxygen atom (O) from oxygen gas to form a lithium oxide molecule.

The chemical formula Li₂O indicates that two lithium ions are combined with one oxygen atom in the compound. This is because lithium has a +1 charge, and since there are two lithium ions, their combined charge is +2. Oxygen, on the other hand, has a -2 charge, so one oxygen atom is sufficient to balance the charges and form a neutral compound.

Hence, the name of the compound formed is Li₂O

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Explanation:

Corrections

- It should be 45 bromine atoms

- Bromine isn't found abundantly as atoms, rather as diatomic molecules

[tex]Br_2[/tex]

Before should show 2 phosphorus atom and 3 bromine molecules to form 2 phosphorus tribromide

The bond is covalent because both bromine and phosphorus is a non-metal

Answer:

Brick

Explanation:

.................

Answer: The volume of given object is 12.0 [tex]cm^{3}[/tex].

Explanation:

Given: Length = 4.0 cm

Width = 1.2 cm

Height = 2.5 cm

Formula to calculate the volume of such an object is as follows.

[tex]Volume = length \times width \times height[/tex]

Substitute the values into above formula as follows.

[tex]Volume = length \times width \times height\\= 4.0 cm \times 1.2 cm \times 2.5 cm\\= 12.0 cm^{3}[/tex]

Thus, we can conclude that the volume of given object is 12.0 [tex]cm^{3}[/tex].

Answer: it has 2 characteristics and they are conductivity and ductility

Explanation:

The conductivity makes them great conductors of electricity

Answer:

It's B guaranteed;)

Conductivity and ductility

Answer:

the correct answer is Group of answer choices

Using models to understand objects and processes better  is not  part of every scientific investigation while collection of relevant empirical evidence,use of logical reasoning and devising hypothesis, making predictions is  a part.

Hypothesis can be defined as an assumption which is made for the sake of argument . It is an interpretation of a practical condition for which action needs to be taken.It is defined as a tentative assumption which is made to test logical consequences.It is an antecedent clause of a statement which is conditional.

It is constructed before research. There are six types of hypothesis 1)simple hypothesis 2) complex hypothesis 3) directional hypothesis 4)non-directional hypothesis 5) null hypothesis 6)casual hypothesis

The hypothesis should be clear and precise, it must be specific and way of explanation of hypothesis should be simple.

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Answer:

pH is a measure of how acidic/basic water is. The range goes from 0 to 14, with 7 being neutral. pHs of less than 7 indicate acidity, whereas a pH of greater than 7 indicates a base. pH is really a measure of the relative amount of free hydrogen and hydroxyl ions in the water.