Three taps A, B, C fill up a tank independently in 10 hr, 20 hr, 30 hr, respectively. Initially the tank is empty and exactly one pair of taps is open during each hour and every pair of taps is open at least for one hour. What is the minimum number of hours required to fill the tank?
option
(A) 8
(B) 9
(C) 10
(D) 11
A nucleus of lead 214 Pb82 emits two electrons followed by an alpha particle. The resulting nucleus will have
option
(A) 82 protons and 128 neutrons
(B) 80 protons and 130 neutrons
(C) 82 protons and 130 neutrons
(D) 78 protons and 134 neutrons
If the sequence of bases in sense strand of DNA is 5'-GTTCATCG-3', then the sequence of bases in its RNA
transcript would be –
(A) 5'-GTTCATCG-3' (B) 5'-GUUCAUCG-3' (C) 5'-CAAGTAGC-3' (D) 5'-CAAGUAGC-3'
During meiosis there is
(A) one round of DNA replication and one division (B) two rounds of DNA replication and one division
(C) two rounds of DNA replication and two division (D) one round of DNA replication and two division
For the reaction A → B, ΔHº = 7.5 mol–1 and ΔSº = 2.5 J mol–1. The value of ΔGº and the temperature at
which the reaction reaches equilibrium are, respectively,
(A) 0 kJ mol–1 and 400 K (B) –2.5 kJ mol–1 and 400 K
(C) 2.5 kJ mol–1 and 200 K (D) 0 kJ mol–1 and 300 K
The solubility product of Mg(OH)2 is 1.0 × 10–12. Concentrated aqueous NaOH solution is added to a 0.01 M
aqueous solution of MgCl2. The pH at which precipitation occur is-
(A) 7.2 (B) 7.8 (C) 8.0 (D) 9.0
In a triangle ABC, it is known that AB = AC. Suppose D is the mid- point of AC and BD = BC = 2. Then the area of the triangle ABC is
option
(A) 2
(B) 2 2
(C) 7
(D) 2 7
A convex lens is used to form an image of an object on a screen. If the upper half of the lens is blackened so that it becomes opaque, then
option
(A) only half of the image will be visible
(B) the image position shifts towards the lens
(C) the image position shifts away from the lens
(D) the brightness of the image reduces
A certain 12-hour digital clock displays the hour and the minute of a day. Due to a defect in the clock whenever the digit 1 is supposed to be displayed it displays 7. What fraction of the day will the clock show the correct time ?
Six is a number perfect in itself, and not because God created the world in six days; rather the contrary is true. God created the world in six days because this number is perfect, and it would remain perfect, even if the work of the six days did not exis
Saint Augustine of Hippo
If I feel unhappy, I do mathematics to become happy. If I am happy, I do mathematics to keep happy.