Chemistry-
General
Easy
Question
After three half lives, the percentage of fraction of amount left is
- 6.35
- 12.5
- 50
- 75
The correct answer is: 12.5
Given 
, we know that 
Or 
Related Questions to study
Chemistry-
in the upper atmosphere is formed by the action of neutron on
in the upper atmosphere is formed by the action of neutron on
Chemistry-General
Chemistry-
The electronic configuration of a diapositive ion 
is 2, 8,14 and its mass number is 56. The number of neutrons present is
The electronic configuration of a diapositive ion is 2, 8,14 and its mass number is 56. The number of neutrons present is
Chemistry-General
Chemistry-
Atoms with the same mass number but having different nuclear charges are called
Atoms with the same mass number but having different nuclear charges are called
Chemistry-General
Chemistry-
After three half lives, the percentage of fraction of amount left is
After three half lives, the percentage of fraction of amount left is
Chemistry-General
Chemistry-
Which of the following are stereospecific reactions?
Which of the following are stereospecific reactions?
Chemistry-General
Chemistry-
Consider the following reactions:
Which of the following are stereospecific reactions?
Consider the following reactions:
Which of the following are stereospecific reactions?
Chemistry-General
Chemistry-
In elimination reaction, the major product is either Saytzeff (more-substituted alkene) or Hofmann product (less-substituted alkene) depending on the nature of the substrate and the nature of the base
Which statement is correct about the reactions?
In elimination reaction, the major product is either Saytzeff (more-substituted alkene) or Hofmann product (less-substituted alkene) depending on the nature of the substrate and the nature of the base
Which statement is correct about the reactions?
Chemistry-General
Chemistry-
Which statement is wrong in the formation of (B) from (A)
Which statement is wrong in the formation of (B) from (A)
Chemistry-General
Chemistry-
The rate of 
reaction depends on the effectiveness of the nucleophile in ejecting the leaving group. Nucleophilicity is the affinity for C atom, while basicity is the affinity for proton
In both cases, a new bond is formed. If a new bond is formed between the anion and proton, the species acts as a base. If a new bond is formed between the anion and C atom, the species acts as nucleophile
Which of the following statements is wrong?
The rate of reaction depends on the effectiveness of the nucleophile in ejecting the leaving group. Nucleophilicity is the affinity for C atom, while basicity is the affinity for proton
In both cases, a new bond is formed. If a new bond is formed between the anion and proton, the species acts as a base. If a new bond is formed between the anion and C atom, the species acts as nucleophile
Which of the following statements is wrong?
Chemistry-General
Chemistry-
Statement 1:Addition of bromine to 
-2-butene yields meso-2,3-dibromo butane
Statement 2:Bromine addition to an alkene is an electrophilic addition
Statement 1:Addition of bromine to -2-butene yields meso-2,3-dibromo butane
Statement 2:Bromine addition to an alkene is an electrophilic addition
Chemistry-General
Physics-
Microwaves from a transmitter are directed normally towards a plane reflector. A detector moves along the normal to the reflector. Between positions of 14 successive maxima, the detector travels a distance 0.14 m. If the velocity of light is 3 
108 m/s, find the frequency of the transmitter –
Microwaves from a transmitter are directed normally towards a plane reflector. A detector moves along the normal to the reflector. Between positions of 14 successive maxima, the detector travels a distance 0.14 m. If the velocity of light is 3 108 m/s, find the frequency of the transmitter –
Physics-General
Physics-
Radio waves coming at 
to vertical are received by a radar after reflection from a nearby water surface & directly. What can be height of antenna from water surface so that it records a maximum intensity (a maxima). (wavelength = 
) (Assume phase changes by 
after reflection)
Radio waves coming at to vertical are received by a radar after reflection from a nearby water surface & directly. What can be height of antenna from water surface so that it records a maximum intensity (a maxima). (wavelength = ) (Assume phase changes by after reflection)
Physics-General
Physics-
Equation of a stationary and a travelling waves are as follows y1 = a sin kx cos 
t and y2 = a sin (t – kx). The phase difference between two points
in the standing wave (y1 ) andis f2 in travelling wave (y2 ) then ratio
Equation of a stationary and a travelling waves are as follows y1 = a sin kx cos t and y2 = a sin (t – kx). The phase difference between two pointsin the standing wave (y1 ) andis f2 in travelling wave (y2 ) then ratio
Physics-General
Physics-
Earthquakes generate sound waves inside Earth. Unlike a gas, Earth can experience both transverse (S) and longitudinal (P) sound waves. Typically, the speed of S waves is about 4 km/s. A seismograph records P and S waves from an earthquake. The first P waves arrive 3.0 min before the first S wave (figure). Assuming the waves travel in a straight line, how far away does the earthquake occur ? (Yearth = 12.8 1010 pa, rearth = 2000 kg/m3 )
Earthquakes generate sound waves inside Earth. Unlike a gas, Earth can experience both transverse (S) and longitudinal (P) sound waves. Typically, the speed of S waves is about 4 km/s. A seismograph records P and S waves from an earthquake. The first P waves arrive 3.0 min before the first S wave (figure). Assuming the waves travel in a straight line, how far away does the earthquake occur ? (Yearth = 12.8 1010 pa, rearth = 2000 kg/m3 )
Physics-General
Physics-
Figure shows a stretched string of length L and pipes of length L, 2L, L/2 and L/2 in options (A), (B), (C) and (D) respectively. The string’s tension is adjusted until the speed of waves on the string equals the speed of sound waves in the air. The fundamental mode of oscillation is then set up on the string. In which pipe will the sound produced by the string cause resonance ?
Figure shows a stretched string of length L and pipes of length L, 2L, L/2 and L/2 in options (A), (B), (C) and (D) respectively. The string’s tension is adjusted until the speed of waves on the string equals the speed of sound waves in the air. The fundamental mode of oscillation is then set up on the string. In which pipe will the sound produced by the string cause resonance ?
Physics-General
