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2 years ago

Select the three hypotheses that explain why being born in the United States leads to a higher chance of developing allergies

Chemistry

1 answer:

ra1l [238]2 years ago

7 0

The three hypotheses that explain why being born in the United States

leads to a higher chance of developing allergies include the following:

The weather patterns in the United States bring more allergens compared to other countries.

Other factors which might influence why there are more children with allergies in the United States include climate, obesity, and the typical western diet with high amounts of processed foods.

The hygiene hypothesis claims that children in the United States are not exposed to enough germs in their infancy and childhood to develop their immune system‘s properly.

Allergies are caused by a host of factors such as :

Climate

Diet

Immune system

These factors is the reason why the chosen hypotheses are the most

appropriate.

Read more about Hypotheses here brainly.com/question/10854125

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But-1-ene can be prepared from butan-1-ol. which type of reaction takes place?

slega [8]

Answer:

Dehydration Reaction

Explanation:

Alcohols can be converted into Alkenes using catalytic amounts of acids as a catalysts.

The water molecule is removed hence, it is called as dehydration reaction.

The reaction is attached.

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2 years ago

Over the years, the thermite reaction has been used for welding railroad rails, in incendiary bombs, and to ignite solid-fuel ro

melamori03 [73]

Answer: The mass of nickel (II) oxide and aluminium that must be used is 18.8 g and 4.54 g respectively.

Explanation:

To calculate the number of moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$ .....(1)

For nickel:

Given mass of nickel = 14.8 g

Molar mass of nickel = 58.7 g/mol

Putting values in equation 1, we get:

$\text{Moles of nickel}=\frac{14.8g}{58.7g/mol}=0.252mol$

For the given chemical reaction:

$3NiO(s)+2Al(s)\rightarrow 3Ni(l)+Al_2O_3(s)$

For nickel (II) oxide:

By Stoichiometry of the reaction:

3 moles of nickel are produced from 3 moles of nickel (II) oxide

So, 0.252 moles of nickel will be produced from $\frac{3}{3}\times 0.252=0.252mol$ of nickel (II) oxide

Now, calculating the mass of nickel (II) oxide by using equation 1:

Molar mass of nickel (II) oxide = 74.7 g/mol

Moles of nickel (II) oxide = 0.252 moles

Putting values in equation 1, we get:

$0.252mol=\frac{\text{Mass of nickel (II) oxide}}{74.7g/mol}\\\\\text{Mass of nickel (II) oxide}=(0.252mol\times 74.7g/mol)=18.8g$

For aluminium:

By Stoichiometry of the reaction:

3 moles of nickel are produced from 2 moles of aluminium

So, 0.252 moles of nickel will be produced from $\frac{2}{3}\times 0.252=0.168mol$ of aluminium

Now, calculating the mass of aluminium by using equation 1:

Molar mass of aluminium = 27 g/mol

Moles of aluminium = 0.168 moles

Putting values in equation 1, we get:

$0.168mol=\frac{\text{Mass of aluminium}}{27g/mol}\\\\\text{Mass of aluminium}=(0.168mol\times 27g/mol)=4.54g$

Hence, the mass of nickel (II) oxide and aluminium that must be used is 18.8 g and 4.54 g respectively.

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3 years ago

In which of these processes is energy transferred by the motion of cold and hot matter? Choose the correct answer.

liubo4ka [24]

Letter B - Convection

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Which macromolecule is ring shaped

liraira [26]

Carbohydrates are ring shaped.

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Water is placed into a sealed jar and has a mass of 22.0 grams. The jar is placed in the freezer and the water turns to ice. The

Serhud [2]

exactly 22.0 grams

because freezing is a physical change not a chemicl change..so nothing is taken away or added

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2 years ago