The answer is C Nuclear Regulatory Commission
These gases all have similar properties under standard conditions: they are all odorless, colorless, monatomic gases with very low chemical reactivity. The six noble gases that occur naturally are helium (He), Neon (Ne), Argon (Ar), Krypton (Kr), Xenon (Xe), and Radon (Rn).
Half-life of a radioactive substance is the time required to reduce the amount of substance to half of its initial amount.
In present case, half-life is material is given as 1000 years and initial amount of material is given as 400 kg
Answer 1) Since, half-life of radio-active substance is 1000 years, therefore after 1st half life, amount of the material will be left to half the initial amount. Hence, amount of substance left after 1000 years = 400/2 = 200 kg.
Answer 2) For 2000 years, radioactive material has crossed 2 times the half life. Therefore , amount of the material will be left to 1/4 the initial amount. Hence, amount of substance left after 2000 years = 400/4 = 100 kg.
Answer 3) For 4000 years, radioactive material has crossed 4 times the half life. Therefore , amount of the material will be left to 1/16 the initial amount. Hence, amount of substance left after 4000 years = 400/16 = 25 kg.
The volume of a box with length 25 cm, height 25 cm and width 1.0 m is 0.0625m³.
Volume of the box which is a cuboid can be calculated by multiplying the length, breadth and height of the given box.
Volume of the box is given by the product of the length of the box, Height of the box and Breadth or width of the box.
Since, the box is a cuboid, hence the formula is given by the products of length, breadth and height.
Given,
length of the box= 25cm = 0.25m
Height of the box =25cm = 0.25m
width of the box= 1m
Volume = length × width × height of box
Volume = 0.25 × 0.25 × 1
Volume = 0.0625m³
The volume of the box is 0.0625m³.
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Your answer is B. radio waves have shorter wavelenghts than microwaves.
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