False. Eyeglasses do not cover all around the eye however safety goggles do
Amu valie on the top and abundsnce percent in decimals on the bottom for each isotope
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.
Answer:
It is in the state of "thermal arrest"
Explanation:
The temperature stays constant during the phase change process . This is because the matter has more internal energy and heat has to be taken away for the solidification process to begin. The energy that is required for a phase change is know as latent heat (which is the energy released or absorbed by a body during a thermodynamic process).
Answer:
For H-Cl, the direction is towards the chlorine atom
For F-CH3, the direction is towards the flourine atom.
Explanation:
The dipole moment is a vector quantity. This implies that it has both magnitude and direction.
Thus, the direction of the dipole moment always points from the positive atom towards the negative atom.
This explains the fact that it points to chlorine in HCl and points to flourine in F-CH3
