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Firlakuza [10]
3 years ago
12

Which type of allergy test, also called a subcutaneous test, introduces dilute solutions of allergens into the skin of the inner

forearm or upper back with a fine-gauge needle?
Chemistry
1 answer:
alexgriva [62]3 years ago
6 0

Answer:

The type of allergy test is scratch test.

Explanation:

In a scratch test also called a skin pri c k test or puncture test, an allergy provoking substance placed on the skin is gradually scratched  into the skin surface with the aid of a needle or lancet so as to detect bodily reactions to allergens. Some of the types allergens whose reactions are generally tested for include pollen, dust mites, molds and foods.

The scratch test takes about 5 to 10 minutes and it could cause slight pain and the may  result in itching feeling at the location where the allergen was introduced.

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Question 3 of 11
daser333 [38]

Answer:

c

Explanation:

b and d are out, the variables are changed. a would be a repetition, not a replication. c uses the same method and variables with a different control group

6 0
3 years ago
Hydrogen cyanide, HCN, can be made by a two-step process. First, ammonia reacts with O2 to give nitric oxide, NO.
stealth61 [152]

Answer:

The mass of HCN is 79.65 g.

The mass of reactant which remain at the end of both reactions is 88.5 g.

Explanation:

Given that,

Mass of ammonia = 50.2 g

Mass of methane = 48.4 g

Hydrogen cyanide, HCN, can be made by a two-step process

Ammonia reacts with O₂ to give nitric oxide NO.

The reaction is,

4NH_{3}+5O_{2}\Rightarrow 4NO+6H_{2}O

We need to calculate the mole of NO

Using given data,

2.25 g NH_{3}=\dfrac{50.2}{17}= 2.95\ mole\ NH_{3} [/tex]

4\ mole NH_{3}\ glose 4\ mol NO

2.95 mol NH₃ will produced 2.95 mol NO

Then nitric oxide reacts with methane,

The reaction is,

2NO+2CH_{4}\Rightarrow 2HCN+2H_{2}O+H_{2}

We need to calculate the mole of methane

Using given data,

mole\ of\ methane=\dfrac{48.4}{16}

mole\ of\ methane = 3.03\ moles

2 mole NO produced 2 mole HCN

2.95 mol NO will produced \dfrac{2.95\times3.03}{3.03}= 2.95 mol HCN

We need to calculate the mass of HCN

Using formula of mass

m=N\times M

Where, N = number of mole

M = molecular mass

Put the value into the formula

m=2.95\times27

m= 79.65\ g

The mass of HCN is 79.65 g.

We need to calculate the mass of NO

Using formula of mass

m=N\times M

Where, N = number of mole

M = molecular mass

Put the value into the formula

m=2.95\times30

m= 88.5\ g

Hence, The mass of HCN is 79.65 g.

The mass of reactant which remain at the end of both reactions is 88.5 g.

4 0
3 years ago
A substance that can be broken down and recycled by bacteria and other decomposes is said to be__________
Stells [14]

Answer:The substance is Biodegradable

Explanation:

When something is biodegradable it can be broken down by organical processes or decomposers.

6 0
3 years ago
2. How much heat is released when 432g of water cools down from 710C to 180C?
nadya68 [22]
The heat released by the water when it cools down by a temperature difference AT

is Q = mC,AT

where

m=432 g is the mass of the water

C, = 4.18J/gºC

is the specific heat capacity of water

AT = 71°C -18°C = 530

is the decrease of temperature of the water

Plugging the numbers into the equation, we find

Q = (4329)(4.18J/9°C)(53°C) = 9.57. 104J

and this is the amount of heat released by the water.
7 0
3 years ago
Lead(II) oxide from an ore can be reduced to elemental lead by heating in a furnace with carbon. Calculate the expected yield of
Lelu [443]

Answer:

53kg is the expected yield of lead

Explanation:

Firstly, in order to solve this question, we need to write the equation of reaction correctly. This is as follows:

PbO(s) + C(s) ---> Pb(l) + CO(g)

We proceed from here. We should get the limiting reactant but this can only be obtained by getting the number of moles of each reactant present.

The formula to use across all boards is that the number of moles is the mass of each of the reactant divided by the molar mass of each of the reactant.

For PBO, mass is 57kg = 57000g

Molar mass of PBO = 223.20g/mol

The number of moles is thus 57,000/223.2 = 255.37 moles

For carbon, mass is also 57kg = 57000g

Molar mass is 12g/mol

Number of moles of carbon = 57000/12 = 4750 moles

From the number of moles, we can see that the number of moles of Carbon is greater than that of PbO. This means that PbO is the limiting reagent.

Hence we use it to calculate percentage yield.

The number of moles of lead formed is the same of number of moles of lead oxide = 255.37 since we have mole ratio of 1 to 1

The molar mass of lead is 207.20g/mol

The mass of lead formed is = moles of lead formed * molar mass of lead = 207.20 * 255.37 = 52,912g which is approximately 53kg

Hence the expected yield is 53kg

6 0
3 years ago
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