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3 years ago

7

3. Science has helped people in several ways. The development of medicine to cure disease, pesticides

1 answer:

USPshnik [31]3 years ago

3 0

Answer:

pesticides is the first one

im sorry i cant give you the second one though

Explanation:

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Which of the following statements is not correct?

Pavlova-9 [17]

Answer: This option is incorrect: <span>B. Covalent compounds are held together by much stronger interparticle forces than are ionic compounds.

Justification:

Ionic bonds, held by ionic compounds, are much stronger than covalent bonds, held by covalent compounds.

In ionic bonds one element yields one or more electrons forming a cation (a positively charged ion) and the other element accepts the electrons forming an anion (a negatively charged ion).

The anion and the cation are electrostatically atracted by each other. This electrostatic atraction force, named ionic bond, is very strong.

As result of this, the ionic compounds form strong crystals with high boiling and fusion points. A good example of this the sodium chloride, formed by the union of cation Na(+) and anion Cl(-).

The covalent bonds are result of sharing electrons and do not form ions. This bond is weaker than the ionic bond.
</span>

4 0

4 years ago

Determine the electrical work required to produce one mole of hydrogen in the electrolysis of liquid water at 298°K and 1 atm. T

Ostrovityanka [42]

Explanation:

The given data is as follows.

$\Delta H$ = 286 kJ = $286 kJ \times \frac{1000 J}{1 kJ}$

= 286000 J

$S_{H_{2}O} = 70 J/^{o}K$ , $S_{H_{2}} = 131 J/^{o}K$

$S_{O_{2}} = 205 J/^{o}K$

Hence, formula to calculate entropy change of the reaction is as follows.

$\Delta S_{rxn} = \sum \nu_{i}S_{i}_(products) - \sum \nu_{i}S_{i}_(reactants)$

= $[(\frac{1}{2} \times S_{O_{2}}) - (1 \times S_{H_{2}})] - [1 \times S_{H_{2}O}]$

= $[(\frac{1}{2} \times 205) + (1 \times 131)] - [(1 \times 70)]$

= 163.5 J/K

Therefore, formula to calculate electric work energy required is as follows.

$\Delta G_{rxn} = \Delta H_{rxn} - T \Delta S_{rxn}$

= $286000 J - (163.5 J/K \times 298 K)$

= 237.277 kJ

Thus, we can conclude that the electrical work required for given situation is 237.277 kJ.

6 0

4 years ago

When light bends around an object, the light is

Elan Coil [88]

The answer is REFRACTED

8 0

3 years ago

Read 2 more answers

Identify and label the Brønsted-Lowry acid, its conjugate base, the Brønsted-Lowry base, and its conjugate acid in each of the f

julia-pushkina [17]

Explanation:

As per Brønsted-Lowry concept of acids and bases, chemical species which donate proton are called Brønsted-Lowry acids.

The chemical species which accept proton are called Brønsted-Lowry base.

(a) $HNO_3 + H_2O \rightarrow H_3O^+ + NO_3^-$

$HNO_3$ is Bronsted lowry acid and $NO_3^-$ is its conjugate base.

$H_2O$ is Bronsted lowry base and $H_3O^+$ is its conjugate acid.

(b)

$CN^- + H_2O \rightarrow HCN + OH^-$

$CN^-$ is Bronsted lowry base and HCN is its conjugate acid.

$H_2O$ is Bronsted lowry acid and $OH^-$ is its conjugate base.

(c)

$H_2SO_4 + Cl^- \rightarrow HCl + HSO_4^-$

$H_2SO_4$ is Bronsted lowry acid and $HSO_4^-$ is its conjugate base.

Cl^- is Bronsted lowry base and HCl is its conjugate acid.

(d)

$HSO_4^-+OH^- \rightarrow SO_4^{2-}+H_2O$

$HSO_4^-$ is Bronsted lowry acid and $SO_4^{2-}$ is its conjugate base.

OH^- is Bronsted lowry base and $H_2O$ is its conjugate acid.

(e)

$O_{2-}+H_2O \rightarrow 2OH^-$

$O_{2-}$ is Bronsted lowry base and OH- is its conjugate acid.

$H_2O$ is Bronsted lowry acid and OH- is its conjugate base.

6 0

3 years ago

How many particles are in 2.0 moles of CH4

Whitepunk [10]

Answer: There are 4.8 x 1024 hydrogen atoms in 2.0 moles of CH4

6 0

2 years ago

Read 2 more answers