A pure substance has a constant composition and cannot be separated into simpler substances by physical means. There are two types of pure substances: elements and compounds. Elements: are pure substances made up of only l type of atom. Atoms of the same element are identical in properties.
Answer:
437.5 kg of first solution and 812.5 kg of second solution should be mixed to get desired solution.
Explanation:
Let the mass of the first solution be x and second solution be y.
Amount solution required = 1250 kg
x + y = 1250 kg....[1]
Percentage of ethanol in required solution = 12% of 1250 kg
Percentage of ethanol in solution-1 = 5% of x
Percentage of ethanol in required solution = 25% of y
5% of x + 25% of y =12% of 1250 kg
x + 5y = 3000 kg...[2]
Solving [1] and [2] we :
x = 437.5 kg , y = 812.5 kg
437.5 kg of first solution and 812.5 kg of second solution should be mixed to get desired solution.
Answer:
Dmitri Mendeleev
Explanation:
Dmitri Mendeleev a Russian Chemist arranged elements on the periodic table according to their atomic mass. He used this arrangement to predict some of the properties of the missing element.
- Dmitri Mendeleev around 1869 described the periodic table.
- The table was based on the periodic law which states that "chemical properties of elements are a periodic function of their atomic weights".
- In the Mendeleev table, elements are arranged by atomic weights with recurring properties in a periodic manner.
C. Homogeneous mixtures These alloys are homogeneous mixtures because they have a uniform composition throughout.
The general properties of Group 1 alkali metals are:
1. They form cations.
2. They are highly reactive.
3. They have a charge of +1.
4. They form ionic compounds.
5. When their oxides or hydroxides are reacted in water, they form alkalis i.e. bases.
6. They are usually soft in nature.
7. They have low densities.
