Explanation:
Metals react with oxygen to form basic oxides while they react with water to form alkaline solutions. Also, acidic oxides are oxides of nonmetals and they react with water to form acidic solutions.
Trends on the period table shows the variation of metallic character as you move across and down the periodic table. Metallic character of a element decreases across the period on the periodic table from left to right because atoms readily accept electrons in their outermost shell to form stable configurations. Metallic character increases as you move down the group in the periodic table and this is because electrons become easier to lose as the atomic radius increases (more outer shells are added), where there is decreasing attraction between the nucleus and the valence electrons.
So down the group, the acidity of oxide reaction with water decreases because the oxides are more basic down the group while across the period, the acidity of oxide increases because acidic oxides are formed as we move across the period.
Answer:
In the option(A) moles of HCl left are 0.100 moles which is wrong, making the option incorrect.
Explanation:
Moles of HCl = n
Molarity of HCl = 1.0M
Volume of HCl solution = 30.0 mL = 0.030 L (1 mL = 0.001L)
Moles of Fe = 
According to recation , 1mol of Fe reacts with 2 mol HCl. Then 0.01 mole of Fe will recat with :
of HCl
This means that HCl uis in excess , hence excessive reagent.
Moles of HCl left unreacted :
= 0.030 mol - 0.020 mol = 0.010 mol
But in the option moles of HCl left are 0.100 moles which is wrong, making the option incorrect.
In 5.70 mol of Hafnium there are 34,326
Answer:
True
Explanation:
The physical changes are reversible in most cases and these changes are not the chemical changes which means that it is only the change in its state not in their nature. Just take the example of water, on cooling it becomes solid and change in color can be seen which is white in solid form and colorless in liquid form. This is also reversible and is a physical change. This means that physical changes can be identified at macroscopic level. Hence the answer is true.
No the sun is the biggest star in the universe.
