Which of the following statements is correct about measurements?
A Accuracy refers to closeness to true value
B Precision refers to closeness of repeated measurements to each other
C Both A and B
D Neither
Accuracy = true value closeness; precision = repeatability.
The dimensional formula of frequency is __________.
A [T⁻¹]
B [L][T⁻¹]
C [M][T⁻²]
D [I]
Frequency is cycles per second → [T⁻¹].
If a light source emits uniformly in all directions, the intensity per unit solid angle is measured in __________.
A watt per steradian
B watt per meter²
C watt per second
D watt per kilogram
Power per unit solid angle units are W/sr.
Which of the following is invariant under time reversal (t→−t)?
A Velocity
B Acceleration
C Position
D Linear momentum sign depends on velocity so changes sign
Position as a function may remain same at time-reversed snapshot; velocities change sign. (Simplified: position is unchanged instantaneously.)
The quantity [M^0 L^0 T^0] is __________.
A length
B mass
C dimensionless
D time
All exponents zero means dimensionless.
What operation on coordinates corresponds to mirror reflection in the yz-plane?
A x→−x, y→y, z→z
B x→x, y→−y, z→−z
C x→−x, y→−y, z→−z
D x→x, y→y, z→z
Reflection in yz-plane flips x sign only.
The unit of moment of inertia is __________.
A kg·m²
B kg/m²
C Nm
D m/s
Moment of inertia units are mass × length^2.
For small errors, the relative error in quotient x/y approximately equals __________.
A (Δx − Δy)/ (x/y)
B Δx/x + Δy/y
C Δx/x + Δy/y (with Δy sign reverse if in denominator)
D Δx/x − Δy/y
Fractional uncertainties add in quadrature for random but linearly for small independent uncertainties approximated as sum.
The parity operation changes a right-handed coordinate system to __________.
A right-handed again
B left-handed
C same as before
D undefined
Parity inversion flips handedness.
An object with mass m moving at constant velocity in free space will conserve __________.
A kinetic energy only
B linear momentum only
C both linear momentum and kinetic energy if no external forces
D neither
In absence of forces, both momentum and kinetic energy remain constant for a single particle (no interactions).
Which of the following is not a space–time symmetry?
A Translation in space
B Rotation in space
C Translation in time
D Chemical reaction
Chemical reaction is not a symmetry operation.
The area of a spherical cap on a sphere of radius r with polar angle α is 2π r^2 (1 − cosα). This formula relates to __________.
A chord length
B solid angle
C circumference
D density
Area of spherical cap relates to solid angle.
In a lab, repeatedly measuring a quantity yields values clustered but all far from true value. This indicates __________.
A high accuracy, low precision
B low accuracy, high precision
C both high
D both low
Clustered values (precision) but far from true (inaccurate) → low accuracy, high precision.
Unit conversion from km/h to m/s uses factor __________.
A divide by 3.6
B multiply by 3.6
C multiply by 3600
D divide by 3600
1 km/h = (1000 m)/(3600 s) = 1/3.6 m/s.
Which of the following is a tensor of rank 2?
A Scalar
B Vector
C Stress tensor
D Number
Stress is a rank-2 tensor.
The physical quantity conserved when a system is invariant under rotation about z-axis is the __________.
A z-component of angular momentum
B x-component of angular momentum
C total mass
D energy
Invariance under rotations around z implies L_z conserved.
The vector triple product a×(b×c) equals __________.
A (a·c) b − (a·b) c
B (a·b) c − (a·c) b
C zero always
D (b·c) a
Standard vector identity: a×(b×c) = b(a·c) − c(a·b).
The best measure of central tendency for skewed data is __________.
A mean
B median
C mode
D range
Median is less affected by outliers for skewed distributions.
Which symmetry combined with charge conjugation and time reversal is often considered (CPT)?
A P only
B C, P, and T together (CPT theorem)
C None
D Gauge
CPT theorem: combined C, P, T symmetry is fundamental in quantum field theory.
In a unit conversion, 1 inch = 2.54 cm exactly because __________.
A arbitrary choice
B defined by international agreement
C derived from fundamental constants
D varies with temperature
1 inch = 2.54 cm is defined by agreement (exact).
Which of the following is conserved in a closed chemical system ignoring nuclear reactions?
A Mass (baryon number)
B Energy only
C Neither mass nor energy
D Charge only
Mass (and matter number) is conserved in chemical processes; energy also conserved but context asked closed chemical system ignoring nuclear → mass conserved.
The gradient operator ∇ acting on a scalar field gives a __________.
A scalar
B vector
C tensor
D matrix
Gradient of scalar is a vector.
An angle measured in steradians is associated with __________.
A planar angle
B solid angle
C linear distance
D volume
Steradian measures solid angle.
If two physical quantities are multiplied, their dimensions __________.
A add (exponents add)
B subtract
C multiply numerically only
D cancel always
Multiply quantities → dimensions’ exponents add.
Which of the following operations does not change the magnitude of a vector but can change its direction?
A Scaling by factor >1
B Rotation
C Reflection with inversion of magnitude
D Multiplication by zero
Rotation rotates direction but preserves magnitude.
The SI base for temperature is __________.
A Celsius
B Fahrenheit
C Kelvin
D Rankine
Kelvin is SI base unit for temperature.
The dimension of kinetic energy (1/2 mv^2) is __________.
A [M][L^2][T^-2]
B [M][L^-1][T^-2]
C [L^2][T^-1]
D [M^2][L][T^-2]
m v^2 → M L^2 T^-2.
In measuring angles, conversion from degrees to radians uses factor π rad = __________ degrees.