Question Discussion & Solution

The correct answer is Silver.

Key Points

• Gold
  • It is one of the softest metals, and this quality makes it easier to design it in various jewelry designs.
  • It is tough making 24 karat gold jewelry. Other metals have to be added to it to increase its durability and strength.
  • If you wish to know what is 24 karat gold, you must understand that 24 karat gold is the purest form of this yellow metal.
  • Although 24 karat is pure gold, a jewelry piece made up of this purity is not solid and flexible enough.
  • When creating and crafting beautiful, intricately designed, and patterned gold jewelry, the metal needs to be added with other alloys to lend it the necessary strength.
  • The metals usually added to gold metal are zinc, nickel, silver, copper, etc. Hence, Option 3 is correct.
  • This is because when gold melts its state will change into a liquid.
  • Gold will like water so it flows and it will become difficult to mold.
  • So copper is added to gold which is there in the liquid state, so it will harden gold a little bit to prevent it from flowing which will be easy to mold gold to make ornaments.

Important Points

• Silver
  • It is a chemical element with the symbol Ag and atomic number 47.
  • A soft, white, lustrous transition metal, it exhibits the highest electrical conductivity, thermal conductivity, and reflectivity of any metal.

Additional Information

• Zinc
  • It is a chemical element with the symbol Zn and atomic number 30.
  • Zinc is a slightly brittle metal at room temperature and has a silvery-greyish appearance when oxidation is removed.
  • It is the first element in group 12 of the periodic table.
• Lead
  • It is a chemical element with the symbol Pb and atomic number 82.
  • It is a heavy metal that is denser than most common materials.
  • Lead is soft and malleable, and also has a relatively low melting point.
  • When freshly cut, lead is silvery with a hint of blue; it tarnishes to a dull gray color when exposed to air.
• Tin
  • It is a chemical element with the symbol Sn and the atomic number 50.
  • Tin is a silvery metal that characteristically has a faint yellow hue.
  • Tin is soft enough to be cut with little force.

Given series U, R, O, L, I, ?

We subtract 3 in each letter we get-

Hence, "F" is the correct answer.

The correct answer is Concave lens.

Key Points

• To treat the eye disease known as myopia or nearsightedness we use the Concave Lens.
• A concave lens is a category of lens that deviates a straight light beam coming from the origin to a diminished, upright, virtual image.
• It can construct both real and virtual images.
• The convex lens is a lens that tends to meet at a point of rays of light that convey parallel to its principal axis which is comparatively thick across the middle and thin at the lower and upper edges.
• A convex lens is used in cameras, correction of Hyperopia, etc.
• Bifocal lenses hold two different prescriptions, an upper part to allow for distance vision and an additional power on the bottom part of the lens to help in close-up focus.
• A bifocal lens is used in people suffering from presbyopia, myopia, hyperopia, and astigmatism.
• The result is eyesight lucidity at both distance and near with one pair of glasses.
• A Compound lens is simple lenses made on a general axis usually in close proximity and often cemented with each other.

Additional Information

Given: 40 × 20 ÷ 28 - 4 + 2

The logic follows here is: 

  
By inserting codes and then using BODMAS Rule:

40 + 20 - 28 ÷ 4 × 2

= 40 + 20 - 7 × 2

= 40 + 20 - 14 

= 60 - 14

= 46

Hence, 46 is the correct answer.

The correct answer is the Helium nucleus.

• Helium nucleus was the source of alpha particles in the Rutherford scattering experiment.
• Ernest Rutherford, a British scientist conducted an experiment and proposed the atomic structure of elements.

Key Points

• Rutherford conducted an experiment by bombarding a thin sheet of gold with α-particles.
• He then analysed the trajectory of these particles after their interaction with the gold foil.
• Since very few α-particles were deflected back, and only a few α-particles had nearly 180^o angle of deflection.
• Hence he concluded that the volume occupied by the positively charged particles in an atom is very small as compared to the total volume of an atom.