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ruslelena [56]
4 years ago
13

2. Chemical changes often cannot be reversed because they

Chemistry
2 answers:
Eduardwww [97]4 years ago
5 0

Answer:

True

Explanation:

WITCHER [35]4 years ago
5 0

Answer:

True...

I’ve tooken a test like that before

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Different of an element have different numbers of neutrons.
inna [77]

Answer:

Isotopes  

Explanation:

This is the definition of isotopes: they are atoms of the same element that contain different numbers of neutrons.

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4 years ago
A coma-like state which may alternate with periods of agitation is likely to be diagnosed as _______ schizophrenia.
mojhsa [17]
Just took the test, catatonic is right.
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3 years ago
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For the Lewis structure above, how many lone pairs are on the P in PCI3
Vinil7 [7]

Answer: C is the correct answer

4 0
4 years ago
2. Determine the molarity of the NaOH solution in each trial. a. Trial 1 Molarity: b. Trial 2 Molarity: 3. Calculate the average
butalik [34]

Answer:

This question is incomplete

Explanation:

This question is incomplete but...

1) You can calculate the molarity of the NaOH for each trial by following the steps below.

The formula for Molarity (M) is

M = number of moles (n) ÷ volume (V)

where the unit of volume must be in Litres or dm³

The unit of molarity is mol/dm³ or mol/L or molar conc (M)

The final answer must have the unit of molarity

If the number of moles is not provided, look out for the mass of NaOH used and then calculate your number of moles (n) as

n = mass of NaOH used ÷ molar mass of NaOH

Where the atomic mass of sodium (Na) is 23, oxygen (O) is 16 and hydrogen (H) is 1. Hence, molar mass for NaOH is 23 + 16 + 1 = 40 g/mol

n = mass of NaOH used ÷ 40

2) Average Molarity will be (Trial 1 Molarity +Trial 2 Molarity) ÷ 2

Answer must be in mol/dm³ or mol/L or M

3) Label the volumentric flask containing the NaOH solution with the answer gotten from (2) above

3 0
3 years ago
If a chemical with a toxicity level of 1 is mixed with a different chemical with a toxicity level of 1, the combined effect of e
ollegr [7]

Answer:

c. antagonism

Explanation:

The toxic effect is that produced by one or several toxic agents on an organism, population or community that is manifested by biological changes. Its degree is assessed by an intensity or severity scale and its magnitude is related to the dose (amount of substance administered, usually expressed per unit of body weight) or the concentration (substance applied in the medium) of the toxic agent.

The effect can be:

- Quantum: consisting of the presence or absence of a characteristic (eg death or existence of tumors).

- Lethal: death by direct action as a result of exposure to a certain concentration of a toxic agent.

- Sublethal: occurs below the level that causes death as a direct result of exposure to a certain concentration of a toxic agent.

- Acute: that caused by the action of chemical substances on living organisms, which manifests rapidly and severely (after a short period of exposure: 0 - 96 h, typically.).

- Chronic: one that occurs, in general, after a prolonged period of exposure (usually manifests after days or years, depending on the species).

- Additive: the magnitude of the effect or simultaneous response of two or more substances is equal to the sum of the effects or responses of each.

- Combined: when two or more substances applied at the same time produce different effects or have different modes of action.

- Enhancement or synergism: when the toxicity of a mixture of chemical agents is greater than expected by the simple sum of the toxicities of the individual agents present in the mixture.

- Inhibition or antagonism: when the toxicity of a mixture of chemical agents is lower than expected by the simple sum of the toxicities of the individual agents present in the mixture.

7 0
4 years ago
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