All categories

3 years ago

What constitutes a positive test for ammonia?

1 answer:

7 0

Ammonia has a characteristic sharp, choking smell. It also makes damp red litmus paper turn blue. Ammonia forms a white smoke of ammonium chloride when hydrogen chloride gas, from concentrated hydrochloric acid, is held near it.

You might be interested in

When the population of organisms in an ecosystem is in balance, we consider the ecosystem to be: A. The ecosystem is in successi

krek1111 [17]

The answer is B. Equilibrium means a state in which opposing forces or influences are balanced.

7 0

3 years ago

What are some genetic diseases?

Svetradugi [14.3K]

Answer:

Down Syndrome- is when you have an extra 21st chromosome.

Turner Syndrome- is when one of the x chromosome is missing or partly there.

Explanation:

There are many more and you can find a complete list online.

8 0

3 years ago

If we start with 1.000 g of strontium-90, 0.805 g will remain after 9.00 yr. This means that the of strontium-90 is ________ yr.

lesantik [10]

The question is incomplete, here is the complete question.

If we start with 1.000 g of strontium-90, 0.805 g will remain after 9.00 yr. This means that the half-life of strontium-90 is ________ yr.

a. 28.8 b. 30.9 c. 35.4 d. 32.2

Answer : The half-life of strontium-90 is 28.8 years.

Explanation :

This is a type of radioactive decay and all radioactive decays follow first order kinetics.

First we have to calculate the rate constant.

Expression for rate law for first order kinetics is given by :

$k=\frac{2.303}{t}\log\frac{a}{a-x}$

where,

k = rate constant

t = time taken for decay process = 9.00 year

a = initial amount or moles of the reactant = 1.000 g

a - x = amount or moles left after decay process = 0.805 g

Putting values in above equation, we get:

$k=\frac{2.303}{9.00}\log\frac{1.00}{0.805}$

$k=0.0241\text{ year}^{-1}$

To calculate the half-life, we use the formula :

$k=\frac{0.693}{t_{1/2}}$

$0.0241\text{ year}^{-1}=\frac{0.693}{t_{1/2}}$

$t_{1/2}=28.8\text{ years}$

Therefore, the half-life of strontium-90 is 28.8 years.

5 0

3 years ago

During which of the following months is the sun likely to illuminate Earth equally from pole to pole?

Gekata [30.6K]

The sun likely to illuminate Earth equally from pole to pole during March and September.

During these two months, both poles receive the same amount of light. This time is called Equinox.

6 0

3 years ago

How many grams does f Cacl2 should be dissolved in 750.0 mL of water to make a 0.100 M solution Cacl2

AVprozaik [17]

Answer:

8.324 g

Explanation:

First we convert 750.0 mL into L:

750.0 mL / 1000 = 0.750 L

Then we calculate the required number of moles of CaCl₂, using the definition of molarity:

Molarity = moles / liters

Molarity * liters = moles

0.100 M * 0.750 L = 0.075 mol

Finally we convert 0.075 moles of CaCl₂ into grams, using its molar mass:

0.075 mol * 110.98 g/mol = 8.324 g

6 0

3 years ago