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3 years ago

How do chemical indicators work? explain

1 answer:

3 0

Chemical indicator, any substance that gives a visible sign, usually by a color change, of the presence or absence of a threshold concentration of a chemical species, such as an acid or an alkali in a solution.

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A mixture consists of sand and an aqueous salt

Alenkinab [10]

Answer is (4).

Explanation:

The given mixture contains an insoluble solid and an aqueous solution of salt. The insoluble solid is sand. 

First we have to separate insoluble solid. Sand can be separated by doing filtration. When we filter the mixture sand can be seen as the residue on the filter paper.

After filtering the mixture, we should collect the filtrate. Filtrate is the salt solution. By doing evaporation we can get the solid salt. 

First and second choices are wrong because after evaporating water filtration cannot be done and salt and sand will be mixed together.

Salt cannot be filtered out because the salt is soluble and it is in aqueous medium. Hence, third choice is wrong

7 0

3 years ago

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If an ion had a charge of (-3), how many valence electrons could be expected

zimovet [89]

Answer:

Key Points. Ionic bonds are formed through the exchange of valence electrons between atoms, typically a metal and a nonmetal.

Explanation:

7 0

3 years ago

The human body excretes nitrogen in the form of urea, NH₂CONH₂. The key step in its biochemical formation is the reaction of wat

Misha Larkins [42]

Mass perventage of nitrogen in urea, arginine, ornithine is 46.67%, 32.2%,21% respectively.

What is Mass perventage ?

Mass percentage is one way of representing the concentration of an element in a compound or a component in a mixture. Mass percentage is calculated as the mass of a component divided by the total mass of the mixture, multiplied by 100.

Molecular mass of urea (NH2CONH2) is= 2× (Atomic mass of N ) + 4 × (Atomic mass of H) + (Atomic mass of C) (Atomic mass of O) = 60

Mass percentage of N = $Total mass of N atoms in the compoundMass of compound×100=2860×100=46.67%$

chemical formula for arginine is C6H14N4O2

molar mass of C6H14N4O2=174g/mol

moles of N atoms in C6H14N4O2=4

mass of N atoms=14*4=56g

mass percent of N in C6H14N4O2=(56/174)*100=32.2%

the chemical formula for ornithine is C5H12N2O2

molar mass of C5H12N2O2=132g/mol

moles of N atoms in C5H12N2O2=2

mass of N atoms in C5H12N2O2=2*14=28

mass percent of N in C5H12N2O2=(28/132)*100=21%

To learn more about urea click on the link below:

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7 0

1 year ago

4. Energy can be conserved by -

mart [117]

Energy can be conserved by efficient energy use.

Answer: Option A

Explanation:

Energy can be transferred from one form to another, but it cannot be destroyed or created. So it can be conserved if efficiently used. Thus efficient usage of energy lead to conservation of energy. Due to conservation of energy, the forces can be renewable and non-renewable.

So, we should know how the input energy can be completely converted to another form of energy leading to efficient usage of energy without any loss. As if there is no loss, input energy will be equal to output energy leading to 100% efficiency.

4 0

3 years ago

What type of element is most abundant: metals, nonmetals, or metalloids?

AnnyKZ [126]

Metals are the most abundant

7 0

3 years ago

Read 2 more answers