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3 years ago

What environmental condition is most likely to trigger the closing of leaf stoma? Wind, heat, darkness, or lack of moisture

Chemistry

2 answers:

erma4kov [3.2K]3 years ago

8 0

Lack of moisture :)

Over [174]3 years ago

4 0

Answer:

The correct answer is " lack of moisture".

Explanation:

The opening or closing of the stomata is regulated in the plant by environmental factors such as light and water availability. In cases of lack of humidity, the stomas are closed preventing water losses in the plant. This also prevents the exchange of gases and the entry of atmospheric carbon dioxide necessary for plant nutrition through the process of photosynthesis.

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lassify these bonds as ionic, polar covalent, or nonpolar covalent. Ionic Polar covalent Nonpolar covalent

jarptica [38.1K]

The question is incomplete, complete question is:

Classify these bonds as ionic, polar covalent, or nonpolar covalent.

Na-F

P-Cl

Cl-Cl

Answer:

Na-F : The bond present is ionic bond.

PCl : The bond present is polar covalent bond.

ClCl : The bond present is non polar covalent bond.

Explanation:

1) Ionic bonds are defined as the bonds which are formed by the complete transfer of electrons from cation (positively charged ions) to anion (negatively charged ions). For Example: NaCl, $BaSO_4$ etc.

Ionic compound :This compound is formed when difference in electronegativity between the atoms is very large.

2) Covalent bond is defined as the bond which is formed by the sharing of electrons between the atoms. For Example: HCl, $CH_4$ etc.

Polar covalent compound: This compound is formed when difference in electronegativity between the atoms is present. When atoms of different elements combine, it results in the formation of polar covalent bond. For Example: $CO_2,NO_2$ etc..

Non-polar covalent compound: This compound is formed when there is no difference in electronegativity between the atoms. When atoms of the same element combine, it results in the formation of non-polar covalent bond. For Example: $N_2,O_2$ etc.

Na-F : Two different atoms with high electronegativity difference

Ionic compound because sodium is metal and fluorine is non metal and the difference between their electronegativity is very large.The bond present is ionic bond.

PCl : Two different atoms with low electronegativity difference

Polar covalent compound because phosphorus and fluorine both are non metal and the difference between their electronegativity is not very large.The bond present is polar covalent bond.

ClCl : Two same atoms with nil electronegativity difference.

Non Polar covalent compound because both are chlorine atom (non metal) and the difference between their electronegativity is zero.The bond present is non polar covalent bond.

5 0

3 years ago

A solution contains 50.0g of heptane (C7H16)and 50.0g of octane (C8H18) at 25 degrees C.The vapor pressures of pure heptane and

AleksandrR [38]

Answer:

a)Pheptane = 24.3 torr

Poctane = 5.12 torr

b)Ptotal vapor = 29.42 torr

c) 81 % heptane

19 % octane

d) See explanation below

Explanation:

The partial pressure is given by Raoult´s law as:

Pa = Xa Pºa where Pa = partial pressure of component A

Xa = mole fraction of A

Pºa = vapor pressure of pure A

For a binary solution what we have to do is compute the partial vapor pressure of each component and then add them together to get total vapor pressure.

In order to calculate the composition of the vapor in part b), we will first calculate the mole fraction of each component in the vapor which is given by the relationship:

Xa = Pa/Pt where Xa = mol fraction of in the vapor

Pa = partial pressure of A as calculated above

Pt = total vapor pressure

Once we have mole fractions we can calculate the masses of the components for part c)

MW heptane = 100.21 g/mol

MW octane = 114.23 g/mol

mol heptane = 50.0 g / 100.21 g/mol = 0.50 mol

mol octane = 50.0 g/ 114.23 g/mol = 0.44 mol

mol total = 0.94 ⇒ Xa= 0.50/0.94 = 0.53 and

Xb= 0.44/0.94 = 0.47

Pheptane = 0.53 x 45.8 torr = 24.3 torr

Poctane = 0.47 x 10.9 torr = 5.12 torr

b) Ptotal = 24.3 torr +5.12 torr = 29.42 torr

c) We will call Y the mole fraction in the vapor to differentiate it from the mole fraction in solution

Y heptane (in the vapor) = 24.3 torr/ 29.42 torr = 0.83

Y octane (in the vapor) = 5.12 torr/ 29.42 torr = 0.17

d) To solve this part we will assume that since the molecular weights are similar then having a mole fraction for heptane of 0.82, we could say that for every mole of mixture we have 0.82 mol heptane and 0.17 mol octane and then we can calculate the masses:

0.82 mol x 100.21 g/mol = 82.2 g

0.17 mol x 114.23 g/mol = 19.4 g

total mass = 101.6

% heptane = 82.2 g/101.6g x 100 = 81 %

% octane = 19 %

There is another way to do this more exactly by calculating the average molecular weight of the mixture:

average MW = 0.83 (100.21 g/mol) + 0.17 ( 114.23 g/mol ) = 102. 6 g/mol

and then having a mol fraction of 0.83 means in 1 mol of mixture we have 0.83 mol heptane and 0.17 mol octane then the masses are:

mass heptane = 0.83 x 100.21 g/mol = 83.2 g

mass octane = 0.17 x 114.23 g/mol = 19.4 g

mass of mixture = 1 mol x MW mixture = 1 mol x 102.6 g/mol 102.6 g

% heptane = (83.2 g/ 102.6 g ) x 100 g = 81 %

% octane = 100 - 81 = 19 %

d)The composition of the vapor is different from the composition of the solution because the vapor is going to be richer in the more volatile compound in the solution which in this case is heptane ( 45.8 vs 10.9 torr).

4 0

3 years ago

18. Which metal is capable of forming more than one cation? <br> Li<br> Ba<br> Al <br> Sn

maw [93]

Answer:

Explanation:

3 0

3 years ago

Complete the following molecular models to represent balanced equations by

trasher [3.6K]

Answer:

I do not know the Answer I'm just trying to get my point

Explanation:

Thank you

7 0

3 years ago

A chemical formula represents:

Ivenika [448]

Answer:

Explanation:

it is a molecular formula that represents the number atoms and type of atoms

7 0

3 years ago