According to his theory when electrons jumps to lower shell the light is emitted and light is a form of energy so option a and d both can be correct answer but opition d is better one
The ANSWER is D
salt In water because it is a simple ion pair Na+1 and Cl-1
Hydrogen Fluoride is similar: H+1 and F-1 and since it is a polar ion pair too it dissolves in water
Should be 33. but I habe no clue
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:
the endangered spices act
Explanation: The US Endangered Species Act (ESA) is our nation's most effective law to protect at-risk species from extinction, with a stellar success rate: 99% of species listed on it have avoided extinction.
