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2 years ago

Which is NOT a reason why organisms communicate with one another?

Chemistry

2 answers:

Anastasy [175]2 years ago

8 0

That would be c to find housing

Tpy6a [65]2 years ago

3 0

Answer:

C. to find housing.

Explanation:

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Question 3(1 point)

SVETLANKA909090 [29]

Answer:

Group 8 is a group (column) of chemical elements in the periodic table. It consists of iron (Fe), ruthenium (Ru), osmium (Os) and hassium (Hs). They are all transition metals.

Explanation:

5 0

2 years ago

Which of the following is unchanged at the end of the CNO cycle?

Musya8 [376]

Answer:

The correct option is: A. carbon-12

Explanation:

The CNO cycle, the abbreviation for the carbon-nitrogen-oxygen cycle, is a catalytic cycle by which the stars produce helium from elemental hydrogen, via a series of nuclear fusion reactions.

This cycle involves the fusion of four protons with carbon ( $_{6}^{12}\textrm{C}$ ), nitrogen isotope ( $_{7}^{13}\textrm{N}$ ), and oxygen isotope ( $_{8}^{15}\textrm{O}$ ), to give an alpha particle and two electron neutrinos and positrons.

The reaction involves the regeneration of carbon ( $_{6}^{12}\textrm{C}$ ) nucleus in the last step.

$_{6}^{12}\textrm{C}$ → $_{7}^{13}\textrm{N}$ → $_{6}^{13}\textrm{C}$ → $_{7}^{14}\textrm{N}$ → $_{8}^{15}\textrm{O}$ → $_{7}^{15}\textrm{N}$ → $_{6}^{12}\textrm{C}$

3 0

2 years ago

How does the appearance of a substance change when it changes phase?

kicyunya [14]

Answer:

Melting: the substance changes back from the solid to the liquid. Condensation: the substance changes from a gas to a liquid. Vaporization: the substance changes from a liquid to a gas. Sublimation: the substance changes directly from a solid to a gas without going through the liquid phase.

Explanation:

6 0

3 years ago

Pyridine (c5h5n) is a particularly foul-smelling substance used in manufacturing pesticides and plastic resins. calculate the ph

zubka84 [21]

Answer is: ph value of pyridine solution is 9.1.

Chemical reaction: C₅H₅N + H₂O → C₅H₅NH⁺ + OH⁻.
c(pyridine - C₅H₅N) = 0.115M.
Kb(C₅H₅N) = 1.4·10⁻⁹.
[C₅H₅NH⁺] = [OH⁻] = x; equilibrium concentration.
[C₅H₅N] = 0.115 M - x.

Kb = [C₅H₅NH⁺] · [OH⁻] / [C₅H₅N].

1.4·10⁻⁹ = x² / (0.115 M -x)

Solve quadratic equation: x = [OH⁻] = 0.0000127 M.
pOH = -log(0.0000127 M) = 4.9

pH = 14 - 4.9 = 9.1.

7 0

3 years ago

Indicate if the following statements are TRUE (T) or FALSE (F):

Aleks [24]

Answer:

a) T

b) T

c) F

d) F

e) T

f) T

g) T

h) F

I) F

j) F

k) F

l) F

Explanation:

The w/v concentration is obtained from, mass/volume. Hence;

%w/v= 50/1000= 5%

In the %w/w we have;

25g/100 g = 25% w/w

In combustion reaction, energy is given out hence it is exothermic.

Neutralization reaction yields a salt and water

% by mass of carbon is obtained from;

8× 12/114 × 100 = 84.1%

All the ionic substances mentioned have very low solubility in water.

One mole of a substance contains the Avogadro's number of each atom in the compound.

There are two iron atoms so one mole contains 2× 55.85 g of iron.

Some sulphates such as BaSO4 are insoluble in water.

Halides are soluble in water hence NaI is soluble in water.

The equation does not balance with the given coefficients because the number of atoms of each element on both sides differ.

The equation represents a decomposition of calcium carbonate as written.

3 0

3 years ago