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gladu [14]
3 years ago
14

When do we classify a disease as epidemic

Chemistry
2 answers:
belka [17]3 years ago
7 0

Answer:

A disease is classifies as an epidemic when there is a sudden increase in cases or in their matter of spread.

Explanation:

djyliett [7]3 years ago
3 0

Explanation:

An epidemic (from Greek ἐπί epi "upon or above" and δῆμος demos "people") is the rapid spread of disease to a large number of people in a given population within a short period of time.

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A substance is analyzed and found to contain 85.7% carbon and 14.3% hydrogen by weight. A gaseous sample of the substance is fou
atroni [7]

Answer:

The empirical formula of the compound is CH2

Explanation:

<u>Step 1:</u> Data given

A substance contains 85.7 % carbon and 14.3 % hydrogen.

The substance has a density of 1.87 g/L

1 mol occupies 22.4 L

Molar mass of carbon = 12 g/mol

Molar mass of hydrogen = 1.01 g/mol

<u>Step 2</u>: Calculate molar mass of the substance

Since 1 mol occupies 22.4 L;

1 mol of this substance = 1.87g/L *22.4 = 41.888 grams

This means the molar mass of the substance is 41.888 g/mol

<u>Step 3:</u> Calculate mass of carbon:

85.8 % is carbon

this means 41.888 * 0.858 = 35.94 grams

<u>Step 4: </u>Calculate moles of carbon

moles C = mass C/ Molar mass C

Moles C = 35.94 grams / 12 g/mol

Moles C = 2.995 moles

<u>Step 5:</u> Calculate mass of hydrogen:

14.3 % is hydrogen

this means 41.888 * 0.143 = 5.99 grams

<u>Step 6 :</u>Calculate moles of hydrogen

Moles H  = 5.99 grams / 1.01 g/mol

Moles H = 5.93 moles

<u>Step 7: </u>Calculate  mol ratio

Ratio C:H = 1:2

The empirical formule = CH2

<u>Step 8</u>: calculate molar formule

Molar mass of empirical formule = 14.02 g/mol

n = Molar mass of substance / molar mass of empirical formule

n = 41.888 / 14.02 = 3

This means we have to multiply the empirical formula by 3

3*(CH2) = C3H6

C3H6 can be propene or cyclopropane

5 0
3 years ago
Light acts like a
8_murik_8 [283]
Particle
wave are the words you're looking for to fill in the blanks
7 0
3 years ago
Read 2 more answers
Find the mass of 250.0 mL of benzene. The density of benzene is 0.90 g/mL.
guapka [62]

Answer:

<h2>225 g</h2>

Explanation:

The mass of a substance when given the density and volume can be found by using the formula

mass = Density × volume

From the question we have

mass = 0.9 × 250

We have the final answer as

<h3>225 g</h3>

Hope this helps you

7 0
2 years ago
An aqueous solution is prepared by dissolving the salt formed by the neutralization of a weak acid by a weak base. Which stateme
Natasha_Volkova [10]

Answer: The values for Ka and Kb for the species in solution must be known before a prediction can be made

Explanation:

1. If Ka is greater than Kb, the salt solution is acidic

2. If Ka is lesser than Kb, the salt solution is basic

3. If Ka is equal to Kb, the salt solution is acidic

8 0
3 years ago
I need help on this question on standard enthalpy of formation
forsale [732]

Answer:

B: Na(s) + Cl2(g) + 3O2(g) = 2NaClO3(s)

Explanation:

We are looking for enthalpy of formation, so we want to see reactance in their natural standard form.

Thus, we want to see the reactance of Na, Cl2 and O2.

The only option that has the correct form of Na, Cl2 and O2 is B.

Na(s) + Cl2(g) + 3O2(g) = 2NaClO3(s)

7 0
2 years ago
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