Find the probability that a student can guess correctly the answers to,
24 or more out of 40, questions on a true-false examination.
Answers
in 2 ways (True or False)
∴ Total ways in which 10 questions can beFind the probability that a student can guess correctly the answers to,
24 or more out of 40, questions on a true-false examination. answered
=210
No. of ways of guessing at least 7questions out of 10
=7 questions correct +8 questions correct +9 questions correct +10questions correct
=10C7(1)7+10C8(1)8+10C9(1)9+10C10(1)10
=120+45+10+1
(a) When an electric charge Q moves against a p.d. V, the amount of work done is given by
W=Q×V ---------------(1)
We know, current , I=tQ
Q=I×t ------------(2)
By ohm's law , IV=R
V=I×R --------------(3)
Putting eqs. (2) and (3) in eq. (1),
W=I×t×I×R
W=I2Rt
Assuming that all the electrical work done is converted into heat energy , we get
Heat produced , H=I2Rtjoules
This relation is known as Joule's law of heating.
(b) Given : P=12W,V=12V,t=60sec
using the equation of power
P=VI
I=P/V=12/12=1A(a) When an electric charge Q moves against a p.d. V, the amount of work done is given by
W=Q×V ---------------(1)
We know, current , I=tQ
Q=I×t ------------(2)
By ohm's law , IV=R
V=I×R --------------(3)
Putting eqs. (2) and (3) in eq. (1),
W=I×t×I×R
W=I2Rt
Assuming that all the electrical work done is converted into heat energy , we get
Heat produced , H=I2Rtjoules
This relation is known as Joule's law of heating.
(b) Given : P=12W,V=12V,t=60sec
using the equation of power
P=VI
I=P/V=12/12=1A
The Ohm's law states that
V=IR
R=V/I=12/1=12ohm
The formula for heat is:
H=I2Rt
H=12×12×60
H=720J
The Ohm's law states that
V=IR
R=V/I=12/1=12ohm
The formula for heat is:
H=I2Rt
H=12×12×60
H=720J
=176
∴ Required Probability =210176=21011×16 =6411
Derive the expression of
series and
Parallel combination.
and write The Heating
effect of Electric currentWhy do we specify 12C? We do not simply state that the mass of a C atom is
12 AMU because elements exist as a variety of isotopes.
Carbon exists as two major isotopes, 12C, and 13C ( 14C exists and has
a half life of 5730 y, 10C and 11C also exist and their half lives are
19.45 min and 20.3 days respectively). Each carbon atom has the
same number of protons and electrons, 6. 12C has 6 neutrons, 13C has
7 neutrons, and 14C has 8 neutrons and so on. So, we must specify
which C atom defines the scale.Atomic Mass
Atomic mass is based on a relative scale and the mass of 12C
(carbon twelve) is defined as 12 amu; so, this is an exact number.
Why do we specify 12C? We do not simply state that the mass of a C atom is
12 AMU because elements exist as a variety of isotopes.
Carbon exists as two major isotopes, 12C, and 13C ( 14C exists and has
a half life of 5730 y, 10C and 11C also exist and their half lives are
19.45 min and 20.3 days respectively). Each carbon atom has the
same number of protons and electrons, 6. 12C has 6 neutrons, 13C has
7 neutrons, and 14C has 8 neutrons and so on. So, we must specify
which C atom defines the scale.
All the masses of the elements are determined relative to 12C.
Average Atomic Mass
Since many elements have a number of isotopes, chemists use average
atomic mass. On the periodic table the mass of carbon is reported as
12.011 amu. No single carbon atom has a mass of 12.011, but in a handful
of C atoms the average mass of a carbon atom is 12.011.
Why 12.011?
If a sample of carbon was placed in a mass spectrometer the
spectrometer would detect two different C atoms, 12C and 13C.
The natural abundance of 14C, 10C and 11C in geologic (i.e. old) samples is so low that we cannotEach question can be answered in 2 ways (True or False)
∴ Total ways in which 10 questions can be answered
=210
No. of ways of guessing at least 7questions out of 10
=7 questions correct +8 questions correct +9 questions correct +10questions correct
=10C7(1)7+10C8(1)8+10C9(1)9+10C10(1)10
=120+45+10+1
=176
∴ Required Probability =210176=21011×16 =6411
detect the effect these isotopes have on the average mass.
From the information collected from the mass spectrometer the average
mass of a carbon atom is calculated.
The mass of 12C is, of course, 12 amu.Carbon is found in nature as the mixture of C-12 and C-13 .If average atomic mass of Carbon is found as 12.011u then Find %abundance of C-12 and C-13?
Find the probability that a student can guess correctly the answers to,
24 or more out of 40, questions on a true-false examination.13C is 1.0836129 times heavier than 12C; so, the mass of 13C is 13.003355
Step-by-step explanation:
Each question can be answered in 2 ways (True or False)
∴ Total ways in which 10 questions can be answered
=210
No. of ways of guessing at least 7questions out of 10
=7 questions correct +8 questions correct +9 questions correct +10questions correct
=10C7(1)7+10C8(1)8+10C9(1)9+10C10(1)10
=120+45+10+1
=176
∴ Required Probability =210176=21011×16 =6411
Answer:
given
no. of questions =40
therefore,
total no. of possible outcomes =40
probability of getting that a student can guess correct or ly for 24
no. of favourable outcomes =24
probability of getting favourable to the student= favourable outcomes/total no. of possible outcomes=24/40= 3/5