Ap_gs_mohit Gupta.docx



In an experiment, 295 mg of copper is deposited when a current of 500 mA passes for 30 minutes. Find the electrochemical equivalent of copper 

32.77a 10-8 kg/coulomb



58.4 kg/ coulomb



109.5 × 108 kg/ coulomb

 Ans: 32.77a 10-8 kg/coulomb

Solution :

Calculate the electrochemical equivalent by the relation as follows: 𝒁 = 𝒎/𝑸

Here, Mass of substance deposited is m and rate of flow is Q Calculate the value if Q by the relation as follows: 𝑸 = 𝑰𝒙𝒕

………………………….(1)

Substitute, I = 500 mA = 0.5 A and 𝑡 = 30 𝑚𝑖𝑛 = 30 𝑥 60 = 1800 𝑠𝑒𝑐 𝑸 = (𝟎. 𝟓 𝑨)𝒙 (𝟏𝟖𝟎𝟎 𝒔𝒆𝒄) 𝑸 = 𝟗𝟎𝟎 𝒄𝒐𝒖𝒍𝒐𝒎𝒃 Substitute the value of Q in equation (1) 𝑍 = 295 𝑥 10−6 / 900 = 32.77 × 10−8 𝑘𝑔/𝐶𝑜𝑢𝑙𝑜𝑚𝑏 𝑍 = 32.77 × 10−8 𝑘𝑔/𝐶𝑜𝑢𝑙𝑜𝑚𝑏



A ball weighing 25 grams is thrown vertically into the air. It takes 15 seconds to reach its highest point. How much time would it take to reach the ground from the highest point? 

More data are required for calculation



Less than 15 seconds



More than 15 seconds



15 seconds

Ans: 15 seconds Solution:

We know that the gravitational force is a conservative force It would take the same time to come back to the starting point, as it takes to go up from the starting point upto the highest point Further, it would come back to the starting point with same velocity directed downwards as it had when it was thrown up. So the time taken to reach the ground from the highest point = time taken to reach the highest point from the ground = 15 seconds.



To obtain Fe and FeO from Fe2O3 the reducing agent used in the upper part of blast furnace is

Carbon



Carbon monoxide



Lime stone



Cool

Ans: Carbon Monoxide Solution: The chemical reaction producing the molten iron is: 𝐹𝑒2 𝑂3 + 3𝐶𝑂 → 2𝐹𝑒 + 3𝐶𝑂2 The furnace reacts with the carbon in the form of coke to produce carbon monoxide and heat: 2 𝐶 + 𝑂2 → 2 𝐶𝑂 The carbon monoxide is the reducing agent for the iron ore and reacts with the iron oxide to produce pure Iron. At the top, where the temperature usually is in the range between 200 °C and 700 °C, the iron oxide is partially reduced to iron oxide, Fe3O4 and carbon dioxide is also obtained By the oxidation of the carbon monoxide. 3𝐹𝑒2 𝑂3 + 3𝐶𝑂 → 2𝐹𝑒 + 3𝐶𝑂2 Carbon dioxide is an escapable gas and will goes out by furnace.



Which of the following yields blue-beads in borax test? 

Co2+



Ni2+



Cd2+



Cr2+



Ans: Co2+

Solution .

The borax test is used to identify the metals. This test is the oldest test. The compounds that are responsible for the colors are Mx(BO2)y salts. In the given metals only cobolt forms the compounds in this form 

Which of the following sales does not display aqueous decomposition? 

KNO3



NaCl



K2SO4



CH3COONA

Ans: Solution: Nacl Nacl does not gives aquous solution because Nacl decompose in the from

𝑁𝑎𝑐𝑙

−

𝑁𝑎2+ + 𝑐𝑙 −2

There is no part of oxygen which is responsible for water formation. 

Germanium possesses

Two valence electrons



Three valence electrons



Four valence electrons



Five valence electrons

Ans: 4 valance electrons Solution: The atomic number of germanium is 32

The configuration of atoms in germanium is given by: 1𝑠 2 2𝑠 2 𝑝4 3𝑠 2 𝑝4 𝑑10 4𝑠 2 𝑝2

By the configuration we can see that only 28 atoms are configured in configuration and 4 atoms are remained here. So the unavailable atoms are 4 in germanium the unavailable atoms are also known as valance electrons. So number of valance electrons of germanium is 4. 

What are Ferrites? 

Magnetic but have low resistance



Magnetic but have high resistance



Non-magnetic with low resistance



Non-magnetic with high resistance

Ans: Magnetic but have high resistance. Solution: Ferrites are explained as any of a group of nonmetallic, ceramic-like, usually ferromagnetic compounds of ferric oxide with other oxides, especially a compound characterized by extremely high electrical resistivity.



Which of the following is used in the blast furnace as flux? 

Fluorspar



Quartzite



Limestone



Ferro-manganese

Ans: Limestone Solution:

Flux is used to remove impurities by creating a “slag” which floats on the surface of the liquid metal and which contains the impurities and can be taken out easily. In blast furnace we used limestone as a flux.When limestone is added into furnace, the temperature of the furnace converts it into the calcinied lime which consequently reduces the liquids temperature of the impurities and help removing the impurities from the furnace



2-pentanol and 3-pentanol can be distinguished by: 

Lucas Test



Tollens reagent



Idoform reaction



Victor Meyer’s Method



Benedict’s Solution:

Ans: Idoform test Solution: The reason of using iodoform test is that 2-pentanol gives the positive result for iodoform test while 3 pentanol does not give the positive iodoform test.



In resistance heating, highest working temperature is obtained from heating elements made of 

Nickel and Copper



Nichrome



Silicon Carbide



Silver

Ans: Nichrome Solution: Nichrome has relatively high resistance and forms an adherent layer of chromium oxide when it is heated for the first time. Material below this layer will not oxidize, preventing the wire from breaking or burning out.