Here we have to calculate the amount of 
ion present in the sample.
In the sample solution 0.122g of ion is present.
The reaction happens on addition of excess BaCl₂ in a sample solution of potassium sulfate (K₂SO₄) and sodium sulfate [(Na)₂SO₄] can be written as-
K₂SO₄ = 2K⁺ +
(Na)₂SO₄=2Na⁺ +
Thus, BaCl₂+ = BaSO₄↓ + 2Cl⁻ .
(Na)₂SO₄ and K₂SO₄ is highly soluble in water and the precipitation or the filtrate is due to the BaSO₄ only. As a precipitation appears due to addition of excess BaCl₂ thus the total amount of ion is precipitated in this reaction.
The precipitate i.e. barium sulfate (BaSO₄)is formed in the reaction which have the mass 0.298g.
Now the molecular weight of BaSO₄ is 233.3 g/mol.
We know the molecular weight of sulfate ion () is 96.06 g/mol. Thus in 1 mole of BaSO₄ 96.06 g of ion is present.
Or. we may write in 233.3 g of BaSO₄ 96.06 g of ion is present. So in 1 g of BaSO₄ 
g of ion is present.
Or, in 0.298 g of the filtered mass (0.298×0.411)=0.122g of ion is present.
Answer:
Bottom left corner of the periodic table
Explanation:
The elements toward the bottom left corner of the periodic table are the metals that are the most active in the sense of being the most reactive. Lithium, sodium, and potassium all react with water, for example.
People use data tables and graphs in many financial careers and when looking at the statistics for something as simple as what they saw on the news, etc. When scientists use them, they’re both using them to see the numbers and the facts. They’re both able to use graphs and data tables to help them. They are different though because scientists use them for science related things like how much a tree grew in a year while everyday people use them to see the average amount of drop outs per year or something along those lines.
Data tables and graphs are very vital to a scientists job. They help them easily collect and organize information to where anyone can read it. It may not be absolutely necessary, but it’s something every scientist uses.
Any scientist doing any sort of research would use them. Whether they’re a biologist, geologist or whatever, they all use graphs and data tables to help them organize their research.
Answer:
For pure substances, the mass and volume will always be the same or will always change the same way because all substance are the same throughout.
While for mixtures, you can have varying amount of each component therefore mass and volume will not change the same way for substances
The heat energy needed is 2928800J. Mass is given as 20 (kg)
