Test: Physics Minor Mock Test- 5 (March 27) - NEET MCQ

Binary number system, in mathematics, positional numeral system employing 2 as the base and so requiring only two different symbols for its digits, 0 and 1, instead of the usual 10 different symbols needed in the decimal system.

Explanation:The materials can be classified by the energy gap between their valence band and the conduction band. The valence band is the band consisting of the valence electron, and the conduction band remains empty. Conduction takes place when an electron jumps from valence band to conduction band and the gap between these two bands is forbidden energy gap. Wider the gap between the valence and conduction bands, higher the energy it requires for shifting an electron from valence band to the conduction band.In the case of conductors, this energy gap is absent or in other words conduction band, and valence band overlaps each other. Thus, electron requires minimum energy to jump from valence band. The typical examples of conductors are Silver, Copper, and Aluminium.In insulators, this gap is vast. Therefore, it requires a significant amount of energy to shift an electron from valence to conduction band. Thus, insulators are poor conductors of electricity. Mica and Ceramic are the well-known examples of insulation material.Semiconductors, on the other hand, have an energy gap which is in between that of conductors and insulators. This gap is typically more or less 1 eV, and thus, one electron requires energy more than conductors but less than insulators for shifting valence band to conduction band.

Given, 10% of substance decays in 10 days
So, let [A]_o=100, [A]_t=100-10=90
So, K=(2.303/t) log ([A]_o/[A]_t)
K= (2.303/10) log (100/90)
K= (2.303/10) (log10-log9)
K= (2.303/10)91-0.9542)     [log9=0.9542]
K= (2.303/10) x 0.0458 day^-1
So, after 24 days,
t= (2.303/K) log (100/[A]t)
24=2.303x10/2.303x0.0458) log [100/[A]_t]
log[100/[A]t]=(24x0.0458)/10=0.1099
100/[A]_t=antiog(0.1099)=1.288
So, [A]_t=100/1.288≈100/1.3
[A]_t=76.9≈77%
The closest answer is 78% which is option A. So the correct answer would be option A
 

More than 99.99% of the mass of any atom is concentrated in its nucleus. If the mass of protons and neutrons (which are in the nucleus of every atom) is approximately one atomic mass unit, then the relative mass of an electron is 0.0005 atomic mass units.

A=1 and B=0
A.A+B
=A2+B [De-Morgan’s theorem)
=1+0
=1
=A

and as we know 1Å = 0.1 nm, so 1.227Å = 0.122 nm

Explanation:Semiconductors are materials that have electrical conductivity between conductors such as most metals and nonconductors or insulators like ceramics. Semiconductor material is used in the manufacturing of electrical components and used in electronic devices such as transistors and diodes.Semiconductors are the basic materials used in the present solid state electronic devices like diode, transistor, ICs etc

There is a direct relation ,
energy= 12400/wavelength(i e ,lambda in angstroms).
given E= 1k e v = 1000 e.v
wavelength = 12400/1000
wavelength= 124/10
wavelength= 12.4

The truth table for 2-input OR gate is as shown in the figure. Thus, the output is zero only when both inputs are zero.

10101 is the binary number to be converted to a decimal number.
To convert, multiply the numbers individually with 2n where n changes according to place value of the number.
(10101)₂= (2⁰× 1) + (0 × 2¹) + (1×2²) + (0×2³) + (1×2⁴)
= 1 + 0 + 4 + 0 + 16
= 21
 

Explanation:When the p-type crystal is grown between relatively wide sections of n-type crystals then the transistor is called NPN transistor.

We have mass – a particle property, in the same equation as wavelength – a wave property. Thus if matter exhibits wave properties, it must be given by equation (3). Equation (3) is the de Broglie equation and represents the wave-particle duality. Hence we say that everything in the Cosmos exhibits a dual nature.

The Davisson-Germer experiment demonstrated the wave nature of the electron, confirming the earlier hypothesis of deBroglie. Putting wave-particle duality on a firm experimental footing, it represented a major step forward in the development of quantum mechanics. The Bragg law for diffraction had been applied to x-ray diffraction, but this was the first application to particle waves.

Using formula for Paschen series,
1/λ=R[(1/3²)-1/n₂²],n₂=4,5,6….
For shortest wavelength, n₂=∞
∴1/λ=R[(1/3²)-1/∞²],n₂=R/9 or λ=9/R ≈ 820.4 nm

An OR gate followed by a NOT gate in a cascade is called a NOR gate. In other words, the gate which provides a high output signal only when there are low signals on the inputs such type of gate is known as NOR gate.

Explanation:In P-type doping, boron or gallium is the dopant. Boron and gallium each have only three outer electrons. When mixed into the silicon lattice, they form "holes" in the lattice where a silicon electron has nothing to bond to. The absence of an electron creates the effect of a positive charge, hence the name P-type.Holes can conduct current. A hole happily accepts an electron from a neighbor, moving the hole over a space. P-type silicon is a good conductor.

1001=1x2³+0x2²+0x2¹+1x2⁰=9
For binary numbers, the digit at the extreme right is referred to as least significant bit (LSB) and the left- most digit is called the most significant bit (MSB). Hence in binary 10010, the most significant bit is 1.
 

In the case of an intrinsic semiconductor (say Si) where each Si is having 4 outermost electrons, its crystal structure consists of making 4 covalent bonds with 4 neighbouring Si atoms. Each bond consists of two electrons.

Now if one of the bonds gets broken due to some reason (collisions or high temperature) then one electron gets free and it will be having sufficient energy to cross the band gap and be ready for conduction- So in intrinsic semiconductors, current flows due to breakage of crystal bonds.
 

The de-broglie equation states, mv=h/l

= v=h/lm

the velocity here is inversely dependant on the masses.

Higher the mass lower will be the velocity.

Therefore, electron will have a higher velocity to produce matter waves of same wavelength.

A hydrogen atom has magnetic properties because the motion of the electron acts as a current loop. The energy levels of a hydrogen atom associated with orbital angular momentum are split by an external magnetic field because the orbital angular magnetic moment interacts with the field.

A spectrum is an assembly of energy levels in the form of radiations emitted by an atom in its excited state. Every atom gives discontinuous line spectra. Each line in the spectra corresponds to a specific wavelength and it is unique to a given element so no two elements give the same pattern of lines in their spectra.

De Broglie wavelength = h/mv,
where h = plancks constant, mv = momentum.
As they move with same momentum, de Broglie wavelength remains constant for all.

The equation of NAND gate is 
Y=Aˉ.Bˉ
When both the terminals are connected together.
A=B=A
Y=Aˉ.Aˉ=Aˉ.Aˉ=Aˉ
Which is nothing but the equation of NOT gate.
Y=Aˉ
Option A is the correct answer.

Concept:

• As per Indian standard for domestic power supply we use A.C current, which is also known as alternating current since they change its polarity at a certain interval of time.
• Now the two principal properties of the A.C electric power supply are Voltage and frequency.
• And we use 220 V and 50 Hz power supply for our common domestic use
• Where 220 V is the potential difference and 50 Hz is its frequency.

Explanation: 

The voltage and frequency of domestic power supply used in India are 220 volt and 50 Hz respectively

A universal gate is a gate which can implement any Boolean function without need to use any other gate type. The NAND and NOR gates are universal gates. In practice, this is advantageous since NAND and NOR gates are economical and easier to fabricate and are the basic gates used in all IC digital logic families.

In nuclear reactors, fission of uranium is carried out by bombarding  a slow moving neutron on uranium which results in emission of 3 more neutrons along with the byproducts  So, cadmium rods are used to absorb extra neutrons in order to achieve controlled chain reaction.

A P-type semiconductor is formed when a trivalent electron deficient impurities such as boron group elements are doped with intrinsic semiconductor. As the impurities are electron deficient, they take electrons from the valence band creating a number of holes. Due this reason conductivity in P-type semiconductor is mainly due to holes rather than electrons.

Unlike a chemical reaction, a nuclear reaction results in a significant change in mass and an associated change of energy, as described by Einstein’s equation. Nuclear reactions are accompanied by large changes in energy, which result in detectable changes in mass. The change in mass is related to the change in energy according to Einstein’s equation: ΔE = (Δm)c2. Large changes in energy are usually reported in kiloelectronvolts or megaelectronvolts (thousands or millions of electronvolts). With the exception of 1H, the experimentally determined mass of an atom is always less than the sum of the masses of the component particles (protons, neutrons, and electrons) by an amount called the mass defect of the nucleus. The energy corresponding to the mass defect is the nuclear binding energy, the amount of energy released when a nucleus forms from its component particles. In nuclear fission, nuclei split into lighter nuclei with an accompanying release of multiple neutrons and large amounts of energy. The critical mass is the minimum mass required to support a self-sustaining nuclear chain reaction. Nuclear fusion is a process in which two light nuclei combine to produce a heavier nucleus plus a great deal of energy.