If a radioactive sample has decayed until only one eighth of the original sample remains unchanged how many half-lives have elapsed?

If a radioactive sample has decayed until only one eighth of the original sample remains unchanged how many half-lives have elapsed?
by

1 Answer

Answer :

3
by
selected by

Related questions

What is the half life of 12 g sample of radioisotope that decayed to 6 g in 28 years?

Description : What is the half life of 12 g sample of radioisotope that decayed to 6 g in 28 years?

Last Answer : 28 years

A journal bearing with hydrodynamic lubrication is running steadily with a certain amount of minimum film thickness. When the load and speed are doubled, how does the minimum film thickness vary? [IES-2008] (a) Remains unchanged (b) Gets doubled (c) Gets reduced to one-fourth of original value (d) Gets reduced to half of original value

Description : A journal bearing with hydrodynamic lubrication is running steadily with a certain amount of minimum film thickness. When the load and speed are doubled, how does the minimum film thickness vary? [IES-2008 ... Gets reduced to one-fourth of original value (d) Gets reduced to half of original value

Last Answer : (a) Remains unchanged

What fraction of an original sample of a radio isotope remains after 3 half-life periods?

Description : What fraction of an original sample of a radio isotope remains after 3 half-life periods?

Last Answer : One eighth remains.

What fraction of an original sample of a radio isotope remains after 3 half-life periods?

Description : What fraction of an original sample of a radio isotope remains after 3 half-life periods?

Last Answer : One eighth remains.

In a consolidated drained test on a normally consolidated clay, the volume of the soil sample during shear (A) Decreases (B) Increases (C) Remains unchanged (D) First increases and then decreases

Description : In a consolidated drained test on a normally consolidated clay, the volume of the soil sample during shear (A) Decreases (B) Increases (C) Remains unchanged (D) First increases and then decreases

Last Answer : (A) Decreases

A sample of gas has a volume of 210 cubic centimeters at a temperature of 250 degrees Kelvin. The temperature is raised to 500 degrees Kelvin while the pressure remains unchanged. What is the new volume of the gas.

Description : A sample of gas has a volume of 210 cubic centimeters at a temperature of 250 degrees Kelvin. The temperature is raised to 500 degrees Kelvin while the pressure remains unchanged. What is the new volume of the gas.

Last Answer : ANSWER: 420 CUBIC CENTIMETERS

How much time is elapsed between the original tape date and the air date on Wheel of Fortune?

Description : How much time is elapsed between the original tape date and the air date on Wheel of Fortune?

Last Answer : I went to see Jeopardy at Radio City Music Hall and the did four episodes in one day. It took about two months before they were aired. I would think WoF would be similar.

If the length of a cable is doubled, its capacitance (a) becomes one-fourth (b) becomes one-half (c) becomes double (d) remains unchanged

Description : If the length of a cable is doubled, its capacitance (a) becomes one-fourth (b) becomes one-half (c) becomes double (d) remains unchanged

Last Answer : (c) becomes double

Fifty micrograms of an isotope have decayed to 12.5 micrograms after 12 hours. What is the half life of the radioisotope?

Description : Fifty micrograms of an isotope have decayed to 12.5 micrograms after 12 hours. What is the half life of the radioisotope? 

Last Answer : ANSWER: SIX HOURS

A radioactive sample has a half life 1500 years. A sealed tube conataining 1g of the sample will contain after 3000 years,

Description : A radioactive sample has a half life 1500 years. A sealed tube conataining 1g of the sample will contain after 3000 years,

Last Answer : A radioactive sample has a half life 1500 years. A sealed tube conataining 1g of the sample will contain ... g of the sample D. 0.01g of the sample

What name is given to the time taken for half the atoms in a sample of a radioactive isotope to decay?

Description : What name is given to the time taken for half the atoms in a sample of a radioactive isotope to decay?

Last Answer : Half-life

Consider the following decay series: `A to B to C to D` Where, A,B and C are radioactive elements with half lives of 4,5 sec, 15 days and 1 sec respec

Description : Consider the following decay series: `A to B to C to D` Where, A,B and C are radioactive elements with half lives of 4,5 sec, 15 days and 1 sec respec

Last Answer : Consider the following decay series: `A to B to C to D` Where, A,B and C are radioactive elements with half ... mol of C, 1/4 mol of D and noen of A

Two radioactive elements X and Y have half lives 6 min and 15 min respectively. An experiment starts with 8 times as many atoms of X as Y. how long it

Description : Two radioactive elements X and Y have half lives 6 min and 15 min respectively. An experiment starts with 8 times as many atoms of X as Y. how long it

Last Answer : Two radioactive elements X and Y have half lives 6 min and 15 min respectively. An experiment starts with 8 times ... B. 12 min C. 48 min D. 30 min

A radioactive element `X`, decays by the sequence and with half-lives, given below, `X underset(30"min")overset(alpha)(rarr) Y underset(2"days")overse

Description : A radioactive element `X`, decays by the sequence and with half-lives, given below, `X underset(30"min")overset(alpha)(rarr) Y underset(2"days")overse

Last Answer : A radioactive element `X`, decays by the sequence and with half-lives, given below, `X underset(30"min" ... D. The mass number of Y is greater than X

In a spent fuel assembly, the radioactive elements having the longest half-lives are the: w) fission products x) actinides y) activation products z) radioisotopes of lead

Description : In a spent fuel assembly, the radioactive elements having the longest half-lives are the: w) fission products x) actinides y) activation products z) radioisotopes of lead

Last Answer : ANSWER: X -- ACTINIDES

`Co^(60)` has half-life of `5.3` years. Find the number of half-lives for `7//8` of the orignal sample to disintergrate.

Description : `Co^(60)` has half-life of `5.3` years. Find the number of half-lives for `7//8` of the orignal sample to disintergrate.

Last Answer : `Co^(60)` has half-life of `5.3` years. Find the number of half-lives for `7//8` of the orignal sample to ... yrs B. 9.2 yrs C. 10.6 yrs D. 15.9 yrs

If a sample that originally contained grams of C14 has gone through two half-lives of decay how much C14 will be left?

Description : If a sample that originally contained grams of C14 has gone through two half-lives of decay how much C14 will be left?

Last Answer : 2.5

What is the use of half lives to determine the age of a sample?

Description : What is the use of half lives to determine the age of a sample?

Last Answer : Carbon-dating

If a sample that originally contained 10 grams of C14 has gone through two half-lives of decay, how much C14 will be left?

Description : If a sample that originally contained 10 grams of C14 has gone through two half-lives of decay, how much C14 will be left?

Last Answer : 2.5

The activity of a radioactive element reduces to `(1//16)th` of its original value in 30 years. Find its half life?

Description : The activity of a radioactive element reduces to `(1//16)th` of its original value in 30 years. Find its half life?

Last Answer : The activity of a radioactive element reduces to `(1//16)th` of its original value in 30 years. Find its half ... B. 75 trs C. 7.5 day D. 75 month

The amount of a radioactive material (having a half life of 100 years) remaining after 400 years will be __________ of its original weight. (A) 1/2 (B) 1/4 (C) 1/8 (D) 1/16

Description : The amount of a radioactive material (having a half life of 100 years) remaining after 400 years will be __________ of its original weight. (A) 1/2 (B) 1/4 (C) 1/8 (D) 1/16

Last Answer : (D) 1/16

The time taken for a radioactive element to reduce to 50% of its original weight is __________ years, if its half life period is 12 years. (A) 24 (B) 18 (C) 6 (D) 36

Description : The time taken for a radioactive element to reduce to 50% of its original weight is __________ years, if its half life period is 12 years. (A) 24 (B) 18 (C) 6 (D) 36

Last Answer : (B) 18

A radioactive isotope has a half-life of 10 days. If today there are 125 g of it left, what was its original weight...

Description : A radioactive isotope has a half-life of 10 days. If today there are 125 g of it left, what was its original weight 40 days earlier  (a) 600 g (b) 1000 g (c) 1250 g (d) 2000 g 

Last Answer : Half life = 10days  The formula which is, 1/(2)^n × original weight = Weight left today.  To obtain the value of n = divide no of days by half life ie.,n= 40/10= 4 n=4 So, 1/(2)^n × original Weight = 125g 1/(2)^4 × Original weight = 125 Original weight = 16×125 = 2000g

`""^(226)Ra` disintegrates at such a rate that after 3160 years, only one fourth of its original amount remains . The half life of `""^(226)Ra` will b

Description : `""^(226)Ra` disintegrates at such a rate that after 3160 years, only one fourth of its original amount remains . The half life of `""^(226)Ra` will b

Last Answer : `""^(226)Ra` disintegrates at such a rate that after 3160 years, only one fourth of its original amount ... B. 3160 years C. 1580 years D. 6230 years

The body protein after eighteen years (A) Remains unchanged (B) Is decomposed only slightly at intervals of one month (C) Is in a constant state of flux (D) Is used only for energy requirement

Description : The body protein after eighteen years (A) Remains unchanged (B) Is decomposed only slightly at intervals of one month (C) Is in a constant state of flux (D) Is used only for energy requirement

Last Answer : Answer : C

The half life of cobalt 60 is 5.3 yers after 10.6years how much of the original cobalt 60 remains?

Description : The half life of cobalt 60 is 5.3 yers after 10.6years how much of the original cobalt 60 remains?

Last Answer : One quarter-Apex

Is one half equal to three eighths plus one eighth?

Description : Is one half equal to three eighths plus one eighth?

Last Answer : Yes. three eights plus one eight equals 4 eights, or onehalf

What is seven and one half minus one eighth?

Description : What is seven and one half minus one eighth?

Last Answer : Seven and three eighths !

Liquefied Petroleum Gas (LPG) in domestic use cylinders is in the liquid form. The density of LPG in liquid form is about __________ of that of water (i.e. 1 gm/c.c). (A) One fourth (B) One third (C) Half (D) One eighth

Description : Liquefied Petroleum Gas (LPG) in domestic use cylinders is in the liquid form. The density of LPG in liquid form is about __________ of that of water (i.e. 1 gm/c.c). (A) One fourth (B) One third (C) Half (D) One eighth

Last Answer : (C) Half

Center of gravity of a solid cone lies on the axis at the height (A) One-fourth of the total height above base (B) One-third of the total height above base (C) One-half of the total height above base (D) Three-eighth of the total height above the base

Description : Center of gravity of a solid cone lies on the axis at the height (A) One-fourth of the total height above base (B) One-third of the total height above base (C) One-half of the total height above base (D) Three-eighth of the total height above the base

Last Answer : (A) One-fourth of the total height above base

Center of gravity of a thin hollow cone lies on the axis at a height of (A) One-fourth of the total height above base (B) One-third of the total height above base (C) One-half of the total height above base (D) Three-eighth of the total height above the base

Description : Center of gravity of a thin hollow cone lies on the axis at a height of (A) One-fourth of the total height above base (B) One-third of the total height above base (C) One-half of the total height above base (D) Three-eighth of the total height above the base

Last Answer : (B) One-third of the total height above base

The diameter of the Links in column should be at least……….of the largest diameter of the longitudinal steel [ A ] One-half [ B ] Three-fourth [ C ] One eighth [ D ] One – fourth

Description : The diameter of the Links in column should be at least……….of the largest diameter of the longitudinal steel [ A ] One-half [ B ] Three-fourth [ C ] One eighth [ D ] One – fourth

Last Answer : [ D ] One – fourth

The Maximum diameter steel in slabs should not exceed --------- the total thickness of the slab [ A ] One-half [ B ] One-fourth [ C ] One-eighth [ D ] One-sixteenth

Description : The Maximum diameter steel in slabs should not exceed --------- the total thickness of the slab [ A ] One-half [ B ] One-fourth [ C ] One-eighth [ D ] One-sixteenth

Last Answer : [ C ] One-eighth

Two light rays will interfere constructively with maximum amplitude if the path difference between them is: w) one wavelength x) one-half wavelength y) one-quarter wavelength z) one-eighth wavelength

Description : Two light rays will interfere constructively with maximum amplitude if the path difference between them is: w) one wavelength x) one-half wavelength y) one-quarter wavelength z) one-eighth wavelength

Last Answer : ANSWER: W -- ONE WAVELENGTH

Madhesh does half work as much as vinith in three eighth of the time. If together they take a day to complete the work, how much time shall vinith take to do it? a) 21 b) 22 c) 23 d) 24

Description : Madhesh does half work as much as vinith in three eighth of the time. If together they take a day to complete the work, how much time shall vinith take to do it? a) 21 b) 22 c) 23 d) 24

Last Answer : A Suppose vinith takes x days to do the work Madhesh takes (2*3/8 x) = 6/8x i.e., 3/4x days to do it (madhesh + vinith’s) 1 day work = 1/9 Therefore 1/x +4/3x = 1/9 (3+4) / 3x = 1/9 7/3x = 1/9 3x = 9*7 X = 63/ 3 =21 Vinith takes 21 days to do the work.

In the impact problems the following conditions must always be satisfied a.The total kinetic energy remains unchanged b.The total linear momentum remains unchanged c.The magnitude of the total linear momentum is multiplied by the coefficient of restitution d.The kinetic energy of the system is reduced by a factor proportional to the coefficient of restitution e.None of the above

Description : In the impact problems the following conditions must always be satisfied a.The total kinetic energy remains unchanged b.The total linear momentum remains unchanged c.The magnitude of the total linear ... is reduced by a factor proportional to the coefficient of restitution e.None of the above

Last Answer : b. The total linear momentum remains unchanged

Assertion :- `Q_("Surr")` is zero for adiabatic process Reason :- Final state of the system remains unchanged in adiabatic process.

Description : Assertion :- `Q_("Surr")` is zero for adiabatic process Reason :- Final state of the system remains unchanged in adiabatic process.

Last Answer : Assertion :- `Q_("Surr")` is zero for adiabatic process Reason :- Final state of the system ... False. D. If both Assertion & Reason are false.

The rating of the Transformer __ when the supply frequency is increased: a) Remains unchanged b) Increases c) Decreases d) None of the above

Description : The rating of the Transformer __ when the supply frequency is increased: a) Remains unchanged b) Increases c) Decreases d) None of the above

Last Answer : Ans: B

As the amount of clay in a soil increases, its water retaining capacity _____ 30 A. Increases B. Decreases C. Remains unchanged D. None of Above

Description : As the amount of clay in a soil increases, its water retaining capacity _____ 30 A. Increases B. Decreases C. Remains unchanged D. None of Above

Last Answer : ANSWER: A

A catalyst remains unchanged at the end of the reaction with regard to (a) Quality (b) Chemical composition (c) Physical state (d) Quantity and chemical composition

Description : A catalyst remains unchanged at the end of the reaction with regard to (a) Quality (b) Chemical composition (c) Physical state (d) Quantity and chemical composition

Last Answer : Ans:(d)

With increasing bond order, stability of a bond (a) Decreases (b) Increases (c) Remains unchanged (d) None of these

Description : With increasing bond order, stability of a bond (a) Decreases (b) Increases (c) Remains unchanged (d) None of these

Last Answer : Ans:(b)

When price of a substitute of commodity falls, the demand for - (1) falls (2) remains unchanged (3) increases at increasing rate (4) rises

Description : When price of a substitute of commodity falls, the demand for - (1) falls (2) remains unchanged (3) increases at increasing rate (4) rises

Last Answer : (1) falls Explanation: Cross Price Effect refers to effect on the demand for a given commodity due to a change in the price of a substitute commodity. A change (increase or decrease) in the ... the given commodity (tea) also decreases. It shifts the demand curve of the given commodity towards left.

In the periodic table of elements, on moving from left to right across a period, the atomic radius – (1) decreases (2) increases (3) remains unchanged (4) does not follow a definite pattern

Description : In the periodic table of elements, on moving from left to right across a period, the atomic radius – (1) decreases (2) increases (3) remains unchanged (4) does not follow a definite pattern

Last Answer : (1) decreases Explanation: The atomic radius is the distance from the atomic nucleus to the outermost stable electron orbital in an atom that is at equilibrium. It tends to decrease across a period from ... usually increases while going down a group due to the addition of a new energy level (shell).

What is the quantity that remains unchanged in a transformer?

Description : What is the quantity that remains unchanged in a transformer?

Last Answer : Frequency

During electrical desalting of crude oil, the electrical conductivity of a mixture of crude oil and water (which ranges between 3 to 8% water) __________ with increase in the amount of water. (A) Decreases (B) Increases (C) Remains unchanged (D) Decreases linearly

Description : During electrical desalting of crude oil, the electrical conductivity of a mixture of crude oil and water (which ranges between 3 to 8% water) __________ with increase in the amount of water. (A) Decreases (B) Increases (C) Remains unchanged (D) Decreases linearly

Last Answer : (B) Increases

Production rate __________ with increased fineness, with a given energy input to the size reduction machine. (A) Decreases (B) Increases (C) Remains unchanged (D) May increase or decrease; depends on the machine

Description : Production rate __________ with increased fineness, with a given energy input to the size reduction machine. (A) Decreases (B) Increases (C) Remains unchanged (D) May increase or decrease; depends on the machine

Last Answer : (A) Decreases

With increase in the capacity of screens, the screen effectiveness (A) Remains unchanged (B) Increases (C) Decreases (D) Decreases exponentially

Description : With increase in the capacity of screens, the screen effectiveness (A) Remains unchanged (B) Increases (C) Decreases (D) Decreases exponentially

Last Answer : (C) Decreases

As the impurities are oxidised, the melting point of iron (A) Decreases (B) Remains unchanged (C) Increases (D) May increase or decrease; unpredictable

Description : As the impurities are oxidised, the melting point of iron (A) Decreases (B) Remains unchanged (C) Increases (D) May increase or decrease; unpredictable

Last Answer : (C) Increases

With increase in absolute humidity, the dew point of an unsaturated mixture of air and water vapor (at constant pressure and temperature). (A) Increases (B) Remains unchanged (C) Decreases (D) Decreases linearly

Description : With increase in absolute humidity, the dew point of an unsaturated mixture of air and water vapor (at constant pressure and temperature). (A) Increases (B) Remains unchanged (C) Decreases (D) Decreases linearly

Last Answer : (A) Increases

In a counter-current extractor, as the axial mixing increases, the extraction efficiency (A) Increases (B) Decreases (C) Remains unchanged (D) Depends on the pressure of the system

Description : In a counter-current extractor, as the axial mixing increases, the extraction efficiency (A) Increases (B) Decreases (C) Remains unchanged (D) Depends on the pressure of the system

Last Answer : (B) Decreases