RRB NTPC 2020 CBT-1 Solved Question Paper with Official Answer Key PDF

RRB NTPC 2020 CBT-1: Fully Solved Paper & Comprehensive Analysis

1. Executive Summary & Difficulty Analysis

The Railway Recruitment Board (RRB) conducted the Non-Technical Popular Categories (NTPC) Computer Based Test-1 (CBT-1) under Notification CEN 01/2019 in multiple phases starting from December 28, 2020. This examination acts as the primary screening gateway for candidates competing for post categories such as Junior Clerk cum Typist, Accounts Clerk cum Typist, Station Master, Goods Guard, and Commercial Apprentice across Indian Railways.

Overall, the difficulty level of the examination ranged from Easy to Moderate. The General Awareness section retained its tradition of being high-yielding yet unpredictable, heavily featuring static General Knowledge (History, Polity, Geography, and General Science) along with prominent Current Affairs from 2019–2020. General Science questions emphasized practical chemical formulas, basic human anatomy, and SI units.

Mathematics was straightforward and predominantly speed-oriented, testing fundamental concepts in Arithmetic (Profit & Loss, Time & Work, Simple & Compound Interest) along with basic applications of Trigonometry, Mensuration, and Algebra. General Intelligence & Reasoning remained the highest-scoring section for most candidates, featuring classical patterns of Coding-Decoding, Syllogisms, Analogy, and Blood Relations with minimal tricky or ambiguous puzzles.

2. Official Exam Pattern & Marking Scheme

3. High-Yield Solved Questions (with Detailed Step-by-Step Solutions)

Question 1

What is the chemical name and formula of Baking Soda, commonly used in cooking and households?

• ASodium Carbonate (Na₂CO₃)
• BSodium Hydrogen Carbonate (NaHCO₃)
• CCalcium Hydroxide (Ca(OH)₂)
• DSodium Hydroxide (NaOH)

Correct Option: (B)

Baking soda is chemically known as Sodium Hydrogen Carbonate or Sodium Bicarbonate, having the chemical formula NaHCO₃.

• •When heated during cooking, it decomposes to release Carbon Dioxide gas (CO₂), which makes cakes and bread soft and spongy:

2 NaHCO₃ + Heat → Na₂CO₃ + H₂O + CO₂

• •Na₂CO₃·10H₂O is Washing Soda (Sodium Carbonate Decahydrate).
• •Ca(OH)₂ is Slaked Lime (Calcium Hydroxide).
• •NaOH is Caustic Soda (Sodium Hydroxide).

Question 2

Which Article of the Constitution of India makes provisions for the establishment of the Finance Commission?

• AArticle 280
• BArticle 324
• CArticle 352
• DArticle 110

Correct Option: (A)

Article 280 of the Indian Constitution empowers the President of India to constitute a Finance Commission every fifth year or at such earlier time as deemed necessary.

• •The Finance Commission recommends the distribution of net tax proceeds between the Union and the States (vertical devolution) and among the States (horizontal devolution).
• •Article 324: Election Commission of India.
• •Article 352: Proclamation of National Emergency.
• •Article 110: Definition of 'Money Bills'.

Question 3

The historic Battle of Plassey was fought in which year between the British East India Company and the Nawab of Bengal?

• A1764
• B1757
• C1761
• D1857

Correct Option: (B)

The Battle of Plassey was fought on June 23, 1757, at Palashi, West Bengal.

• •It was fought between the forces of the Nawab of Bengal, Siraj-ud-Daulah, and the British East India Company led by Robert Clive.
• •The betrayal of Mir Jafar (commander-in-chief of Nawab's army) led to the defeat of Siraj-ud-Daulah.
• •This battle marked the political consolidation and beginning of British rule in India.
• •Note: Battle of Buxar took place in 1764, Third Battle of Panipat in 1761, and the First War of Indian Independence in 1857.

Question 4

Which is the highest mountain peak in Peninsular India (South India)?

• ADoddabetta
• BAnamudi
• CGuru Shikhar
• DKalsubai

Correct Option: (B)

Anamudi (2,695 meters / 8,842 feet) is the highest peak in Peninsular India and the Western Ghats.

• •It is located in the Ernakulam and Idukki districts of Kerala, within the Eravikulam National Park.
• •Doddabetta (2,637 m) is the highest peak in the Nilgiri Mountains.
• •Guru Shikhar (1,722 m) is the highest peak in the Aravalli Range (Rajasthan).
• •Kalsubai (1,646 m) is the highest peak in Maharashtra (Sahyadri range).

Question 5

In computer networking, what does the abbreviation HTTP stand for?

• AHypertext Transfer Protocol
• BHigh Transfer Text Protocol
• CHypertext Transmission Process
• DHyper Terminal Transfer Program

Correct Option: (A)

HTTP stands for Hypertext Transfer Protocol.

• •It is an application-layer protocol used for transmitting hypermedia documents, such as HTML web pages, over the internet between a web browser (client) and a web server.
• •HTTPS stands for Hypertext Transfer Protocol Secure, which utilizes SSL/TLS encryption for secure data transfer over port 443, whereas standard HTTP uses port 80.

Question 6

An article is bought for ₹800 and sold for ₹960. Find the profit percentage earned on the transaction.

• A15%
• B20%
• C25%
• D16.66%

Correct Option: (B)

Given:

Cost Price (CP) = ₹800

Selling Price (SP) = ₹960

1. Profit = SP - CP

Profit = 960 - 800 = ₹160

1. Profit Percentage = (Profit / CP) × 100

Profit % = (160 / 800) × 100

Profit % = (1 / 5) × 100 = 20%

Question 7

A can complete a piece of work in 12 days, while B can complete the same work in 15 days. If they work together, in how many days will the work be completed?

• A6 days
• B6⅔ days
• C7½ days
• D8 days

Correct Option: (B)

• •Work done by A in 1 day = 1/12
• •Work done by B in 1 day = 1/15

Combined 1-day work of (A + B) = (1/12) + (1/15)

Taking the LCM of 12 and 15, which is 60:

= (5 + 4) / 60

= 9 / 60

= 3 / 20

Total days required to complete the work = 20 / 3 = 6⅔ days (or 6.67 days).

Question 8

Find the value of the trigonometric expression: (sin 30° + cos 60°) / (1 + tan 45°)

• A0.25
• B0.50
• C1.00
• D1.50

Correct Option: (B)

Standard trigonometric values:

• •sin 30° = 1/2
• •cos 60° = 1/2
• •tan 45° = 1

Substitute these values into the expression:

Numerator = sin 30° + cos 60° = (1/2) + (1/2) = 1

Denominator = 1 + tan 45° = 1 + 1 = 2

Result = Numerator / Denominator = 1 / 2 = 0.50

Question 9

Calculate the difference between the Compound Interest (compounded annually) and Simple Interest on a principal sum of ₹5,000 at an interest rate of 10% per annum for a duration of 2 years.

• A₹25
• B₹50
• C₹75
• D₹100

Correct Option: (B)

The standard formula for the difference (D) between Compound Interest (CI) and Simple Interest (SI) for a time period of 2 years is:

Difference (D) = P × (R / 100)²

Where:

• •Principal (P) = ₹5,000
• •Rate of Interest (R) = 10%

Substituting the values:

D = 5000 × (10 / 100)²

D = 5000 × (1 / 10)²

D = 5000 × (1 / 100)

D = ₹50

Question 10

The radius of a circular park is 7 meters. What is the area of the park? (Take π = 22/7)

• A154 m²
• B308 m²
• C44 m²
• D616 m²

Correct Option: (A)

Formula for the area of a circle = π × r²

Given radius (r) = 7 m

Area = (22 / 7) × 7 × 7

Area = 22 × 7 = 154 m²

Question 11

In a certain code language, if STATION is coded as TUBUJPO, how will RAILWAY be coded in that same language?

• ASBJMXBZ
• BSBJMAXZ
• CTCJMXBZ
• DSBJLXBZ

Correct Option: (A)

Analyze the pattern from STATION → TUBUJPO:

• •S (+1) → T
• •T (+1) → U
• •A (+1) → B
• •T (+1) → U
• •I (+1) → J
• •O (+1) → P
• •N (+1) → O

The logic applied is a forward shift of +1 to every letter.

Applying the same rule to RAILWAY:

• •R (+1) → S
• •A (+1) → B
• •I (+1) → J
• •L (+1) → M
• •W (+1) → X
• •A (+1) → B
• •Y (+1) → Z

Hence, RAILWAY is coded as SBJMXBZ.

Question 12

Complete the given number series by choosing the correct option:

4, 9, 19, 39, 79, ?

• A119
• B139
• C159
• D169

Correct Option: (C)

Analyze the mathematical relation between successive numbers:

• •4 × 2 + 1 = 9
• •9 × 2 + 1 = 19
• •19 × 2 + 1 = 39
• •39 × 2 + 1 = 79

Following the pattern (n × 2 + 1):

Next term = 79 × 2 + 1

Next term = 158 + 1 = 159

Question 13

Statements:

1. All dogs are mammals.
2. All mammals are animals.

Conclusions:

I. All dogs are animals.

II. Some animals are dogs.

Select the correct option:

• AOnly Conclusion I follows
• BOnly Conclusion II follows
• CNeither Conclusion I nor II follows
• DBoth Conclusion I and Conclusion II follow

Correct Option: (D)

• •Venn Diagram Representation: The circle representing 'Dogs' is entirely inside 'Mammals', and 'Mammals' is entirely inside 'Animals'.
• •Conclusion I (All dogs are animals): Since the entire set of Dogs lies inside Mammals, which lies inside Animals, Dogs are completely contained within Animals. Thus, Conclusion I follows.
• •Conclusion II (Some animals are dogs): Since all dogs are animals, the subset of animals containing dogs represents a portion of all animals. Therefore, Conclusion II follows.
• •Hence, Both Conclusions I and II follow.

Question 14

Pointing to a photograph, Rohit said, "She is the daughter of my grandfather's only son." How is the girl in the photograph related to Rohit?

• AMother
• BSister
• CAunt
• DCousin

Correct Option: (B)

Deconstruct the relationship step-by-step from Rohit's perspective:

1. "My grandfather's only son" → Rohit's father (since he is the only son).
2. "Daughter of my grandfather's only son" → Daughter of Rohit's father.
3. The daughter of Rohit's father is Rohit's sister.

Therefore, the girl in the photograph is Rohit's Sister.

Question 15

Which human organ stores Bile juice secreted by the Liver?

• APancreas
• BGallbladder
• CKidney
• DStomach

Correct Option: (B)

• •Bile juice is continuously synthesized and secreted by the Liver.
• •It is concentrated and temporarily stored in the Gallbladder before being released into the duodenum (small intestine) to assist in the emulsification and digestion of fats.
• •Pancreas: Secretes pancreatic juice containing enzymes like trypsin, amylase, and lipase.
• •Kidney: Filters blood and removes nitrogenous waste products (urine).

4. Quick Official Answer Key (At a Glance)

5. Category-Wise Expected Cut-Off Marks

Note: The actual shortlisting cut-off marks in RRB NTPC CBT-1 vary significantly across different Railway Recruitment Boards (RRBs) like Chandigarh, Mumbai, Allahabad, Patna, Kolkata, and Chennai, and are normalized out of 100.

6. Frequently Asked Questions (FAQ)

• •Q: What is the negative marking policy in RRB NTPC 2020?

A: There is a penalty of 1/3 mark (0.33 mark) for every wrong answer submitted in RRB NTPC CBT-1 and CBT-2. Marks are neither awarded nor deducted for unattempted questions.

• •Q: Where can I check the official response sheet and answer key?

A: Candidates can log into their official RRB regional website (e.g., rrbcdg.gov.in, rrbmumbai.gov.in) using their Registration Number and Date of Birth to view their attempted response sheet, official master answer key, and raise objections when the window opens.

• •Q: How will normalization be calculated across multiple shifts?

A: RRB utilizes a modified mean-standard deviation normalization formula. It adjusts raw scores based on the comparative average performance and standard deviation of marks obtained across all candidate shifts, ensuring that candidates in harder shifts are evaluated fairly against those in easier shifts.