Answer:
A unit of mass used to express atomic and molecular weights, equal to one-twelfth of the mass of an atom of carbon-12. It is equal to approximately 1.66 x 10-27 kg.
Explanation:
Its A. because it measures the rate of the decay of the isotope
Answer: 250 ml of stock solution with molarity of 12.0 M is measured using a pipette and 250 ml of water is added to volumetric flask of 500 ml to make the final volume of 500 ml.
Explanation:
According to the dilution law,

where,
= concentration of stock solution = 12.0 M
= volume of stock solution = ?
= concentration of diluted solution= 6.00 M
= volume of diluted acid solution = 500 ml
Putting in the values we get:


Thus 250 ml of stock solution with molarity of 12.0 M is measured using a pipette and 250 ml of water is added to volumetric flask of 500 ml to make the final volume of 500 ml.
Answer:
A radical is a group of atoms of elements carrying a charge, e.g., chlorate [ClO3–]. Radicals or ions are formed by losing or gaining electrons. When an electron is gained the group of atoms acquire a negative charge and is called a negative radical or negative ion.
I believe it is C, as helium is one of the lightest noble gases making the particles move faster.