RRB JE (Railways Junior Engineer) CBT CBT 1 - Full Test 4 Free Online Test

Let the no. of cubes of side a that can be made by melting the given cuboid = n

Total volume of these cubes = na³

Total volume of all the smaller cubes is equal to the volume of the original cube

As a = 2

⇒ 8 cm × 4 cm × 27 cm = 2³ × n

⇒ n = 108

An amalgam is an alloy of mercury with another metal. Almost all metals can form amalgams with mercury, the notable exceptions being iron, platinum, tungsten, and tantalum. Silver - mercury amalgams are important in dentistry, and gold - mercury amalgam is used in the extraction of gold from ore. 

Malaria is an infectious disease caused by parasitic protozoans and is spread by vectors such as the female Anopheles mosquito. Malaria causes symptoms that typically include fever, tiredness, vomiting, and headaches.

The objective of the Basel Convention on the Control of Transboundary Movements of Hazardous Wastes and their Disposal. Also to protect human health and the environment against the adverse effects of hazardous wastes.

sin² 15° + sin² 20° + sin² 25° + ..... sin² 75°

= [cos (90° - 15°)]² + [cos (90° - 20°)]² + ..... [cos (90° - 75°)]² [cos (90 - θ) = sinθ]

= cos² 75° + cos² 70° + cos² 65° + ...... cos² 15°

= cos² 15° + cos² 20° + cos² 25° + ..... cos² 75°

Ratio of efficiency of A, B and C = 15 ∶ 10 ∶ 6

Ratio of time of A, B and C = 1/15 ∶ 1/10 ∶ 1/6 = 2 ∶ 3 ∶ 5

Let A alone can complete the work in = 2x days

B alone can complete the work in = 3x days

And C alone can complete the work in = 5x days

According to the question,

1/2x + 1/3x + 1/5x = 1/25

⇒ 31/30x = 1/25

⇒ x = 155/6

So, C alone can complete the work in = 5x = 5 × 155/6 = 775/6 days

Short trick:

Total work = (15 + 10 + 6) × 25 = 31 × 25 = 775

∴ C will complete the work = 775/6

Pench National Park is located in Madhya Pradesh

The correct answer is option 2, Neither I nor II follows, as both statements I and II are courses of actions and not conclusions. 

Quinine is an alkaloid found in the stem bark of the cinchona tree. It has been used to treat malaria since the early 1600s. It also is used as a medication for babesiosis.

As we know, the compound ratio for the ratios (a : d), (b : e), (c : f) is (abc : def)

Hence, for the given ratios, compound ratio is obtained as,

⇒ [3x/(4x + 3)] × [(5x - 2)/2x] = 14/9

⇒ 3 × 9 × (5x - 2) = 2 × 14 × (4x + 3)

⇒ 135x - 54 = 112x + 84

⇒ 135x - 112x = 54 + 84

⇒ 23x = 138

⇒ x = 138/23

∴ x = 6

German silver or simply nickel silver is metallic alloy used for mainly production of musical instruments. German silver made up of 60% copper, 20% zinc and 20% nickel.

The given number is 22⁴⁷¹

The unit digit of 2.

⇒ 2¹ = 2

⇒ 2² = 4

⇒ 2³ = 8

⇒ 2⁴ = 6

⇒ 2⁵ = 2

Here, the digit is repeating after every 4^th power.

Now,

⇒ 22⁴⁷¹ = 22⁴⁶⁸ × 22³ = (22⁴)¹¹⁷ × 22³

The unit digit of expression (22⁴)¹¹⁷ × 22³

⇒ (22⁴)¹¹⁷ × 22³ = 6 × 2 × 2 × 2 = 8

Hence, the unit digit of 22⁴⁷¹ = 8.

As, the length of two tangents drawn from an external point to a circle are equal

⇒ AD = AF

⇒ BD = BE

⇒ FC = CE

∴ All options are correct

• Though the Indian Constitution is federal and envisages dual polity, it provides for only single citizenship unlike U.S.A that has dual citizenship.
• This feature has been adopted from the British Constitution. 

A halophyte is a plant that grows in salty water coming into contact with saline water through its roots or by salt spray, such as in saline semi-deserts, mangrove swamps, marshes and sloughs and seashores.

Clearly, Sarthak finally walking in the direction towards - North.

• The shape of the Atlantic Ocean is of an S’ shaped basin.
• It extends between Europe and Africa to the east and the Americas to the west.
• The Atlantic Ocean is the second largest ocean in the World after the Pacific Ocean.

The Psophometer measures AF(Audio Frequency) signal level and noise.

• Marble cancer refers to the corrosion of structure made up of marble by the action of sulphuric or nitric acid.
• In the last decade, there was huge industrial growth nearby Taj Mahal, and the huge amount of sulfur and nitric gases are released in the atmosphere by industries.
• These gases mixed with rain cause acid rain. And The Taj Mahal is losing its white shine because of marble cancer.

Gunmetal, also known as red brass, is a type of bronze an alloy of copper, tin, and zinc. Proportions vary by source, but 88% copper, 8-10% tin, and 2–4% zinc is an approximation. 

• It was used mainly for making guns and bullets. Now it is superseded by Steel.
• Gunmetal is used extensively for making heavy machinery parts as it can withstand high pressure and is corrosion resistant.

Rusting of Iron takes place due to redox reaction.

• Rust is an iron oxide, a usually red oxide formed by the redox reaction of iron and oxygen in the presence of water or air moisture.
• Fe + O₂  → Fe₂O₃ (Iron (III)oxide)

Hence, 4 is the correct answer.

Hence, the answer is figure given in option 1.

The pattern followed here is,

16 × 5 = 80,

80 - 16 = 64,

64 × 4 = 256,

256 - 64 = 192,

192 ​× 3 = 576,

576 - 192 = 384,

384 ​× 2 = 768

Hence, 192, 768 are the missing number.

• The main function of ribosomes is the synthesis of vital proteins inside the cell.
• The ribosome molecules link amino acids, which are the building blocks of protein structures, in different combinations to form different proteins.
• The linking process is governed by messenger RNA molecules.

The given expression:

[2²+ 3² + 4² + 5² + 6² + 7² + 8² + 9² + 10² + 11²]

= [1² +2²+ 3² + 4² + 5² + 6² + 7² + 8² + 9² + 10² + 11²] – 1

= The sum of squares of first 11 natural numbers – 1

[We know that, the sum of square(s) of 1^st n natural numbers =

Here n = 11]

= The sum of squares of first 11 natural numbers – 1

= 506 – 1

= 505

• Das Kapital, also known as Capital. Critique of Political Economy by Karl Marx is a foundational theoretical text in materialist philosophy, economics and politics. 
• Marx aimed to reveal the economic patterns underpinning the capitalist mode of production, in contrast to classical political economists such as Adam Smith, Jean-Baptiste Say, David Ricardo and John Stuart Mill.

• Escape velocity is the minimum velocity an object must have in order to escape the gravitational field of the earth.
• The formula for escape velocity is  

where

G = Universal gravitational constant

M = Mass of the planet or moon (kg)

R = Radius of the planet or moon (m)

The formula for annual compound interest is:

Where:

A = the future value of the investment/loan, including interest

P = the principal investment amount (the initial deposit or loan amount)

r = the annual interest rate

n = the number of times that interest is compounded per year

t = the number of years the money is invested or borrowed for.

n = 1 [As the amount is compounded annually]

t = 3 years

r = 10% compounded annually

A = P + Compound Interest (CI)

Now from the formula,

⇒ CI = 1.331P – P = 0.331P

Now the formula for simple interest:

Interest = Principal × Rate percent × Time ÷ 100

Here, principal = Rs. P

Rate percent = 10

Time = 3 years

Putting the values in the formula, we get

Simple interest for 3 years:

 = Rs. P × 10 × 3 ÷ 100

= Rs. 0.3P

According to the question, the difference between the compound interest and the simple interest for 3 year at 10% is Rs. 31.

⇒ 0.331P – 0.3P = 31

⇒ 0.031P = 31

⇒ P = Rs. 1000

Argon gas is used in electric bulbs to stop the oxygen in the light bulbs from corroding the hot tungsten filament which in result increase the life of a bulb.