Answer: (E) 300 bq
Explanation:
Half life is the amount of time taken by a radioactive material to decay to half of its original value.
Radioactive decay process is a type of process in which a less stable nuclei decomposes to a stable nuclei by releasing some radiations or particles like alpha, beta particles or gamma-radiations. The radioactive decay follows first order kinetics.
Half life is represented by 
Half life of Thallium-208 = 3.053 min
Thus after 9 minutes , three half lives will be passed, after ist half life, the activity would be reduced to half of original i.e. 
, after second half life, the activity would be reduced to half of 1200 i.e. 
, and after third half life, the activity would be reduced to half of 600 i.e. 
,
Thus the activity 9 minutes later is 300 bq.
Answer: 0.082 atm L k^-1 mole^-1
Explanation:
Given that:
Volume of gas (V) = 62.0 L
Temperature of gas (T) = 100°C
Convert 100°C to Kelvin by adding 273
(100°C + 273 = 373K)
Pressure of gas (P) = 250 kPa
[Convert pressure in kilopascal to atmospheres
101.325 kPa = 1 atm
250 kPa = 250/101.325 = 2.467 atm]
Number of moles (n) = 5.00 moles
Gas constant (R) = ?
To get the gas constant, apply the formula for ideal gas equation
pV = nRT
2.467 atm x 62.0L = 5.00 moles x R x 373K
152.954 atm•L = 1865 K•mole x R
To get the value of R, divide both sides by 1865 K•mole
152.954 atm•L / 1865 K•mole = 1865 K•mole•R / 1865 K•mole
0.082 atm•L•K^-1•mole^-1 = R
Thus, the value of gas constant is 0.082 atm L k^-1 mole^-1
Negative symbol which means that gain of electron.
I not sure about the answer sorry!! if you will get wrong in your book
This angle is obtained when all four pairs of outer electrons repel each other equally. The bond angles in ammonia and in water are less than 109.5° because of the stronger repulsion by their lone pairs of electrons.
