Energy that is lost as heat

Hibernation is _______. A. An example of an abiotic cycle b. Triggered by changes in the weather c. Caused only by biotic factor

natta225 [31]

The correct answer is option b, that is, triggered by changes in the weather.

Hibernation refers to a state of lower metabolism and inactivity usually witnessed in endotherms. This condition is featured by a slow heart rate, slow breathing, low metabolic rate, and low body temperature. It assists the majority of the endotherms to thrive in the cold seasons. For example, hibernation of a bear in winters. Therefore, weather change can stimulate hibernation.

6 0

3 years ago

Antimony has two naturally occuring isotopes, 121 Sb and 123 Sb . 121 Sb has an atomic mass of 120.9038 u , and 123 Sb has an at

valina [46]

Answer:

Percentage abundance of 121 Sb is = 57.2 %

Percentage abundance of 123 Sb is = 42.8 %

Explanation:

The formula for the calculation of the average atomic mass is:

$Average\ atomic\ mass=(\frac {\%\ of\ the\ first\ isotope}{100}\times {Mass\ of\ the\ first\ isotope})+(\frac {\%\ of\ the\ second\ isotope}{100}\times {Mass\ of\ the\ second\ isotope})$

Given that:

Since the element has only 2 isotopes, so the let the percentage of first be x and the second is 100 -x.

For first isotope, 121 Sb :

% = x %

Mass = 120.9038 u

For second isotope, 123 Sb:

% = 100 - x

Mass = 122.9042 u

Given, Average Mass = 121.7601 u

Thus,

$121.7601=\frac{x}{100}\times 120.9038+\frac{100-x}{100}\times 122.9042$

$120.9038x+122.9042\left(100-x\right)=12176.01$

Solving for x, we get that:

x = 57.2 %

Thus, percentage abundance of 121 Sb is = 57.2 %

percentage abundance of 123 Sb is = 100 - 57.2 % = 42.8 %

6 0

3 years ago

Calculate the percent ionic, the percent covalent, and the bond length (in picometers) of a chemical bond between phosphorus and

kirza4 [7]

Answer:

The correct option is;

4 percent ionic, 96 percent covalent, 222 pm

Explanation:

The parameters given are;

Phosphorus:

Atomic radius = 109 pm

Covalent radius = 106 pm

Ionic radius = 212 pm

Electronegativity of phosphorus = 2.19

Selenium:

Atomic radius = 122 pm

Covalent radius = 116 pm

Ionic radius = 198 pm

Electronegativity of selenium= 2.55

The percentage ionic character of the chemical bond between phosphorus and selenium is given by the relation;

Using Pauling's alternative electronegativity difference method, we have;

$\% \, Ionic \ Character = \left [18\times (\bigtriangleup E.N.)^{1.4} \right ] \%$

Where:

Δ E.N. = Change in electronegativity = 2.55 - 2.19 = 0.36

Therefore;

$\% \, Ionic \ Character = \left [18\times (0.36)^{1.4} \right ] \% = 4.3 \%$

Hence the percentage ionic character = 4.3% ≈ 4%

the percentage covalent character = (100 - 4.3)% = 95.7% ≈ 96%

The bond length for the covalent bond is found adding the covalent radii of both atoms as follows;

The bond length for the covalent bond = 106 pm + 116 pm = 222 pm.

The correct option is therefore, 4 percent ionic, 96 percent covalent, 222 pm.

4 0

3 years ago

Given the reaction:

tino4ka555 [31]

4 moles of NaCl is produced from 2 moles of Na₂CrO₄.

Explanation:

Given reaction is

PbCl₂(aq) + Na₂CrO₄(aq)→ PbCrO₄(s) + 2 NaCl (aq)

It is the balanced equation which means that on both sides of the equation, number of atoms of each element are equal.

From the above balanced equation it says that molar ratio of Na₂CrO₄ to NaCl is 1 : 2.

That is 1 mole of Na₂CrO₄ produces 2 moles of NaCl, so the molar ratio is 1:2.

2 moles of Na₂CrO₄ produces 4 moles of NaCl.

So the molar ratio of Na₂CrO₄ to NaCl is 2: 4.

6 0

3 years ago

Which branch of the chemical industry usually requires advanced degrees? Marketing product development R & D corporate manag

fredd [130]

Answer: R & D is the correct option.

Explanation:

Research and development department of a chemical industry requires individuals holding advanced degrees because :

This will help the chemical industry to come up with new developments and advancements in preparation of the chemical products like :green methods to prepare certain chemicals which usually involves handling of toxic substances.
Formulation and development of the new chemical substitutes
Improvement of chemical product at microscopic level.

4 0

3 years ago