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The oxidation number of Bismuth in BiONO3 is +3.

The oxidation number of Oxygen in BiONO3 is -2.

The oxidation number of Nitrogen in BiONO3 is +5.

(3) If statement 1 is true but statement 2 is false

Photocell is a device whose electric properties are affected by light

(4) By lowering the temperature

Characteristics of Nuclear force:

(i) It is the strongest force in nature.

(ii) It is spin dependent. 

(iii) It is a short range force. 

(iv) It is exchange force. 

(v) It is charge independent. 

(vi) Nuclear force has the property of Saturation. 

(vii) It is a non-central force.

We know that electric potential V \(=\frac1{4\pi\varepsilon_0}\frac qr\)

V = kq/r

∵ k = 1/4 πɛ₀ = 9 x 10⁹

Electric potential \(=\frac{9\times10^9\times2\times1.6\times10^{-19}}{1\times10^{-10}}\)  

= 28.8 x 10^-10+10

V = 28.8 volt

Myopia: It is a defect of human eye which can see near objects clearly but cannot see the far objects clearly. It can be corrected by using a concave lens of suitable focal length.

X-rays are used:

(i) as a diagnostic tool in medicine to detect feature of bones, foreign bodies like bullets and stones in body. 

(ii) in the treatment of certain cancer. 

(iii) for detecting faults, cracks and flaws in metal casting. 

(iv) in the investigation of structure of crystals. 

(v) to cause photoelectric effect.

Option : (B) Both A and R are true and R is not the correct explanation of A.

Chlorobenzene is less reactive towards nucleophilic substitution reaction due to the delocalization of the electrons of C-Cl bond and a partial double bond character develop in the bond which make it difficult for nucleophile to cleave C-Cl bond.

When Nitro group present at ortho and para position it withdraw electrons from benzene ring and helps to attack of Nucleophiles on haloarene. that's why. Nucleophilic Substitution increases.

U = \(\vec m\).\(\vec B\)

or U = m Bcosθ

U – Magnetic potential energy, 

m – magnetic moment of the magnetic dipole. 

B – Uniform magnetic field.

Magnetic Declination (θ): The angle between the magnetic meridian and geographic meridian at a place is called Magnetic Declination at that place. 

Magnetic Inclination or angle of dip (I): It is the angle between the direction of total magnetic field of earth and a horizontal line in magnetic meridian.

V_d = \(\frac{I}{nAe}\)

Where, I – current 

n – number of electrons per unit volume. 

A – area of cross section. 

e – charge on electron

Answer: (4) 1

\(\sqrt2\) ​ =1.41421356237 

Since 2 has 1 significant digit,

Hence the \(\sqrt2\) ​ has only one significant digit.

 \(\sqrt2\) ​ =1.41421356237 

Since 2 has 1 significant digit,

Hence the \(\sqrt2\) ​ has only one significant digit.

There are six life processes that all living organisms perform. They are movement, respiration, growth, reproduction, excretion and nutrition. Let us learn about all of these briefly.

Boiling point of alcohol is higher than its corresponding alkane because due to high electro-negativity of oxygen in alcohols inter molecular hydrogen bond is present. Therefore to break this hydrogen bond in alcohols more amount of energy is required. Therefore their boiling points are high.

Correct option is (D) (A)-(III), (B)-(IV), (C)-(I), (D)-(II)

(A) Chloroform + Aniline → (III) Distillation

(B) Benzoic acid + Napthalene →(IV) Crystallisation

(C) Water + Aniline → (I) Steam distillation

(D) Napthalene + Sodium chloride → (II) Sublimation

The neighbouring soil to the earth electrode shall be kept moist where necessary, by periodically pouring water through a pipe where fitted along with it or by pouring water in the immediate vicinity of the earth electrode.

Periodical visual inspection of all earth electrodes connection wherever available, shall be carried out to ensure their rigidity and other signs of deterioration. 

Grounding conductor, pad, rods etc. should have following specifications: 

a. Copper : 91.8 to 94.9% 

b. Zinc : 2.0 to 3.0% 

c. Tin : 0.8 to 1.5% 

d. Lead : 2.0 to 2.5% 

e. Iron : 0.5 to 1.0%

Impurities must be limited to the percentage specified below: 

a. Nickel : 0.3% maximum. 

b. Antimony : 0.3% maximum. 

c. Manganese : 0.04% maximum. 

d. Phosphorous : 0.04% maximum. 

Resistance of internal body tissues (Not including skin) : 300 Ω. Resistance of body including skin : 500 to 3000 Ω.  

Equipment operating handles deserve special attention because of the higher probability for co-incidence of adverse factors. For example, 

a. Hand operation equipment such as grounding switches and disconnecting switches requires the presence of operator near a grounded structure at a point where opening of an energised circuit can some times result in an arc to the structure or perhaps mechanical failure and electrical break down of a switch insulator. A large percentage of fatal accidents from voltage gradients are in fact associated with operating handles. Hence in order to avoid above problems following should be an additional safety factors: 

1. Use closer mesh in the vicinity of operating handle area (150-mm approx.) and operating handle shall be directly connected to the earthing mat. 

2. Use higher resistance surfacing such as crushed rock or both in order to bring down the values of touch potential and step potential.

a. Earthing conductors in outdoor areas shall be burried 500 mm below finished grade level unless stated otherwise. 

b. Minimum 6000 mm spacing between rod pipe electrode shall be provided unless stipulated otherwise. 

c. Earthing conductor around the building shall be burried in earth at a minimum distance of 1500 mm from the outer boundary of building. 

d. Earthing conductors embedded in the concrete floor of the building shall have approximately 100-mm concrete cover. 

e. Earthing conductors along their run on columns, beams, walls etc. shall be supported by suitable cleats at intervals of 750 mm. 

f. Earthing conductors crossing the road shall be either installed in hume pipes or laid at greater depth to suit the site conditions. 

g. Whenever earthing conductors cross underground service ducts, pipes, trenches, under ground service ducts, pipes, trenches, tunnels, railway track etc. it shall be laid 800 mm below them. 

h. Earthing conductor shall be burried 1000 mm outside the switchyard fence. Every alternate post of the fence and gates shall be connected to earthing loop by one lead. 

i. Each earthing lead from the neutral of the power transformer shall be directly connected to a rod or pipe or plate electrode treated earth pit, which in turn shall be connected to station earthing.  

a. The magnetic fluxes produced by the three phases in a multi core power cable almost cancel put each other, since the vector sum of these currents at any instant is zero and practically there is no residual magnetic flux around the cable. In case of single core cable, the magnetic flux induces the voltage in the metallic sheath. 

b. When the cable conductor is carrying alternating current, for safe and reliable operation, the metallic sheath must be grounded. If the metallic sheath is at one end the potential of the unearthed end could be much above the earth potential. If both ends are grounded, a circulating current is induced in the metallic sheath. 

c. The maximum acceptable induced voltage under normal load current operation is limited by corrosion and safety considerations. 

d. Code of practice of earthing (IS 3043) as well as electricity council London recommended permissible induced voltage level of 65 Volts.

Hence keeping above all points in mind metallic sheath and armour of all multi core power cables shall be earthed at both end equipment and switchgear end. Sheath and armour of single core power cable shall be earthed ate switchgear end only. The sheaths of shielded control cables should be grounded at both ends to eliminate induced potentials. 

An advantage of use of copper is in addition to their high conductivity, has the advantage of being resistant to underground corrosion. Copper is cathodic with respect to other metals that are likely to be burried in the vicinity. 

Disadvantages of use of copper are, 

a. Grid of copper forms a galvanic cell with burried steel structures, pipes and any of the lead based alloys that might be present in cable sheaths, it is likely be hasten the corrosion of the latter. 

b. Use of tinned copper conductor accelerates and concentrates the natural corrosion of metal in small area however cell potential with respect to steel and zinc reduces by about 50% and practically eliminates this potential with respect to lead. 

Because the excitatory action of current (stimulation of nerves and muscle, induction of cardiac atrial or ventricular fibrillation) are linked to the changes of current magnitude especially when making and breaking of the current. To produce the same excitatory effects the magnitude of direct current flow of constant strength in 2 to 4 times greater than that of alternating current. 

Because the most dangerous touch contacts involves and outside the fence are usually accessible to the general public. In order to minimise the effect of step potential and touch potential following two philosophies could be adopted. 

a. Inclusion of the fence within the ground grid area and 

b. Placement of fence outside the ground grid area – not safe to use.

With this effective area is increased and reduces ground grid resistance substantially and maximum ground – grid voltage rise as well. In this case the perimeter conductor of grid normally either follow the fence line, or parallel to it at a short distance about 0.5 m – 1.5 m outside. In either case, the perimeter ground conductor and fence are bonded electrically at frequent intervals. 

The resistivity decreases and the salt content is expressed in percent by weight of the contained moisture. It will be noted that the curve flattens off at about 5% salt content and a further increase in salt content gives little decrease in the soil resistivity. 

a. During lightning, surges should be discharged to ground, otherwise it will puncture the equipment insulation and it is possible only when lightning arrestor is grounded properly. 

b. In order to make it effective, the ground terminal of lighting arrestor should be connected direct to the tank of transformer. This will eliminate voltage build up due to earth resistance. For example for each ohm of earth resistance the voltage build up for 5000 Amps discharge current is 5 kV. Soil resistivity a should be minimum and may be it is 3.5 ohm per meter. 

When a ground fault occurs, there is a tendency of neutral shift with consequent change in voltage on the un-faulted phases. This phenomenon is called neutral floating or neutral displacement. 

The temperature co-efficient of resistivity for soil is negative, but it is negligible for temperature above freezing point. Below 0°C the water in the soil begins to freeze and introduces a tremendous increase in the temperature co-efficient, so that as the temperature becomes lower the resistivity rises enormously.  

a. For touch voltages upto approximately 50V the value of impedance of the skin varies widely with surface area of contact, temperature, respiration etc. even for one person. 

b. For higher touch voltages in order of approximately 50V to 100V the skin impedance decreases considerably and becomes negligible when the skin breaks down. 

c. Wet hand contact resistance becomes very low at any voltage. 

d. With increase in frequency, impedance of skin decreases. 

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As per IS: 3043, 1987, measurement of earth resistivity should be carried out annually or biannually and value should be recorded. 

Specify the time taken for toasting a bun and wrapping of patty along with bun in a fast-food joint.

Example: Nainital is a beautiful hill-station in Uttarakhand. 

1. Nainital is a beautiful hill-station… 

2. It is surrounded by… 

3. …in Uttarakhand. 

4. …above sea-level. 

5. …high mountain peaks 

6. Nainital is a very… 

7. …especially during winter… 

8. …popular tourist spot, 

9. …when the snow falls.

a. Step and tough potential will increase more than maximum tolerable value. 

b. Under single line to ground fault the voltage to earth of the two healthy phases rises from their normal phase to neutral voltage to full line voltage, which may result in insulation break down. 

c. The capacitive current in two healthy phases increases √3 times the normal value. 

d. The capacitive current in the faulty phase is 3 times its normal value. 

e. Experience shows that capacitive current in excess of 4 amps may be sufficient to maintain an arc in the ionized path of the fault and this persistent arc phenomenon is called ARCING GROUND, which ultimately cause high voltage build up. Some time these voltage builds up to 5 to 6 times its normal value, which results in break down of insulation. 

f. Being fault current low, it is difficult to isolate fault. 

(b) TR

TR is the unit of Refrigeration.

The purpose of grounding is to maintain the surface under and around a station ate as nearly zero potential as possible with reference to absolute earth so that operating staff who walk in the station yard and tough equipments are ate earth potential and when faults occur there is safety to staff and equipments.  

In order to enumerate this, let us first find out the effects of current and voltage developed during fault condition. 

Fibrillation current is actually function of individual body weight

For 50 kgs body weight: fibrillation current (IB) = 0.116/ª ts (Limited to 0.03 – 3 sec. Range) 

Where ts = duration of current exposure in sec. 

Note = Above equation results = 116 mA for 1 sec. and 367 mA for 100 sec. For 70 kgs body weight: fibrillation current (IB) = 0.157/ª ts 

Note = Above equation results = 157 mA for 1 sec. and 496 mA for 100 sec. 

Above times are very - very important from the point view of clearing the fault. Above limit dictates that grounding should e such that current magnitude through human body should not increase the specified values. 

In order to ensure above following have been done. 

1. Current conductor have been burried in ground 

a. At the depth of 600 mm in switchyard. Depth 600 mm is normally selected because of freezing or drying out, the Resistivity of upper layers could vary with seasons, while the Resistivity of lower soil layers remains nearly constant. 

b. Horizontal grid conductors are more effective in reducing the danger of high step and touch voltages on the earth surface by creating equipotential surface during fault conditions. 

c. At the depth of 800 mm else where. Here depth is kept more because to care for under grounding services. Example laying of power cables, drainage etc.

2. 25-mm dia copper rod electrodes have been driven in soil. 

a. Upto 5 meters depth in 220 kV switchyard. 

b. Upto 3 meters elsewhere. Why only 5 meters and 3 meters depths have been selected is that the resistance is diminishes rapidly with the first few feet of driving, but less so at depths greater than 2 to 3 meters in soil of uniform resistivity. 

These lengths are adopted in selecting the ground electrodes.

3. 4-inch layer of gravel in 220 kV switchyard has been used. Purpose of using gravel is by doing steps 1,2 above tough and step potential are computed and compared with tolerable potential and found as given below.

Equipment earthing ensures safety. 

Grounding of non-current carrying metallic parts is called equipment grounding. For instance no-current carrying parts include the following:

a. Motor body, switchgear metal enclosure, transformer tank, conduits of wiring etc. 

b. Support structures, tower, poles etc. in the neighborhood of electrical circuits. 

c. Sheath of cables. 

d. Body of portable equipment such as iron, oven, etc.  

Correct answer is

(b) He can apply oil in the night and wash his hair everyday before leaving home.

Grounding of neutral point of equipment is called system grounding. For instance grounding of generator neutral, transformer neutral etc. 

It is important because: 

a. Earth fault protection is based on the method of neutral earthing. 

b. System voltage during earth fault depends on neutral earthing. 

c. It is a protection against arcing grounds, unbalanced voltages with respect to earth and lighting. 

There are two types 

a. System grounding.

b. Equipment grounding. 

a. = sum(C4:C7)

b. Sort in ‘Sort and Filter’ group under Data tab

c. = max(D4:D7)

d. = average( C4:C7)

e. = sum(E4: E7)

Grounding electrode: A conductor driven in the earth and used for collecting ground current from or dissipating ground current into the earth. 

Grounding system: Comprises all interconnected grounding facilities in a specific area. 

Grounding system: Comprises all interconnected grounding facilities in a specific area. 

(a) Zeroth law of Thermodynamics

Zeroth law of Thermodynamics law of thermodynamics states that ‘When two bodies are in the thermal equilibrium with a third body, they are in thermal equilibrium with each other'.