`.^(238)U=238.05079 u" "._(2)^(4)He=4.00260 u`
`._(90)^(234)Th=234.04363 n" "._(1)^(1)H=1.00783 u`
`._(90)^(237)Pa=237.0512l u`
Here the symbol `Pa` is for the element protacttntum `(Z=91)`.
(b) Show that `.^(238)U`. can not spontaneously emit a proton .

Initially the earth was a fire-ball, slowly it has cooled to form earth crust and its different layers. At the beginning ""_(92)^(238)U was present and no ""_(82)^(206) Pb was there. With the passage of time, uranium decayed to ""_(82)^(206)Pb The decay process is : ""_(92)^(238)U underset((x alpha, y beta))to ""_(82)^(206)Pb , t_(1//2) of ""^(238)U = 4.5 xx 10^(9) yrs A sample of rock from south America contains equal number of atoms of ""^(238)U and ""^(206)Pb . The age of the rock will be :

On analysis a sample of Uranium was found to contain 0.2777 g of ""_(82)Pb^(206) and 1.667 g of ""(92)U^(238) . The half-life periodof ""_(92)^(238) is 4.51 xx 10^(9) years. If all the lead were assumed to have come from decay of ""_(92)^(238) , What is the age of the earth ?

If the total binding energies of ""_(1)^(2)H, ""_(2)^(4)He, ""_(26)^(56)Fe and ""_(92)^(235)U nuclei are 2.22, 28.3, 492 and 1786 MeV respectively, identify the most stable nucleus out of the following

A sample of U^(238) (t_(1//2)= 4.5 xx 10^(9) yrs) is found to contains 23.8g U^(238) and 20.6g Pb^(206) , the age of ore is

The element 'X' in the following reaction is : ""_(90)^(234)Th to 7_(2)^(4)He + 6""_(-1)^(0)e + X

If u = cot^(-1)sqrt(tan alpha ) - tan ^(-1)sqrt(tan alpha) then tan (pi/4-u/2) is a) sqrt(tan alpha) b) sqrt(cot alpha) c) tan alpha d) cot alpha

For the reaction X _(2) O _(4 (l)) to 2 XO _(2 (g)) , Delta u = 2.1 kcal mol ^(-1), Delta S = 20 cal K ^(-1) mol ^(-1) at 300 K. Calculate Delta G and predict whether the reaction is spontaneous at 300 K

Which of the following represents the first law of thermodynamics?(1) ΔU=q+w (2)ΔH=q+W, (3) Δ U=H+pΔV (4) ΔU=pΔV