ArtofBlockchain

Difficulty - Medium

Total Plays - 1,616

Allowed Time - 10 sec

Best time - 0.900

Which opcode is deprecated but still callable?

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#A

#B

#C

#D

Explanation:
CALLCODE is deprecated due to unsafe context handling. It remains callable for backward compatibility but should never be used in new designs.

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Shubhada Pande
@ShubhadaJP • May 14, 2026

May 14, 2026
1.9K

Smart Contract Fundamentals Hub: EVM Execution, Solidity First Principles, and Mainnet-Ready Mental Models

Most weak smart contract candidates do not fail because they have never seen Solidity syntax. They fail when the conversation moves one level deeper. What actually happens when a function...

Like 3 Replies 1
abushaker jamil
@hRZ80yi • Jan 3, 2026

Jan 3, 2026
378

Looking for Guidance in My Blockchain Journey --- How Do I Get My First Full-Time Blockchain Developer Role?

I’ve been learning blockchain for about 1.5 years, and it has become something I’m truly passionate about. Even though I don’t come from a traditional tech background. I completed a...

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Difficulty - Medium

Total Plays - 1,600

Allowed Time - 10 sec

Best time - 1.367

Which opcode differentiates EOAs from contracts?

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#A

#B

#C

#D

Explanation:
EXTCODESIZE returns zero for EOAs and non-zero for deployed contracts. This distinction is commonly used for contract detection, though it has edge cases.

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Aditi Rao
@aditi-rao • Apr 16, 2026

Apr 16, 2026
4.2K

How Do I Switch From UI/UX Design to a Blockchain or Web3 Career?

Has anyone here transitioned from regular UI/UX design into blockchain or Web3? I have three years of experience working on SaaS and web apps, but now I am curious about...

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Difficulty - Medium

Total Plays - 1,604

Allowed Time - 10 sec

Best time - 1.582 sec

Which opcode returns remaining gas?

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#A

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#D

Explanation:
GASLEFT returns the amount of gas remaining in the current execution context. It is commonly used for gas-aware logic and debugging.

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Difficulty - Medium

Total Plays - 1,600

Allowed Time - 10 sec

Best time - 3.422

Which type consumes exactly one storage slot regardless of value?

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#A

#B

#C

#D

Explanation:
bytes32 always occupies a full 32-byte storage slot. Smaller types may be packed together, but bytes32 always stands alone.

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Shubhada Pande
@ShubhadaJP • Jun 20, 2026

Jun 20, 2026
2.3K

Proof-Based Hiring in Web3: Hiring Signals, Recruiter Screening, JD Proof Lines, and Shortlist Quality

This hub is for founders, hiring managers, recruiters, Web3 talent teams, and technical screeners who want to evaluate blockchain candidates through visible proof instead of polished claims, keyword-heavy resumes, or...

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Difficulty - Medium

Total Plays - 1,591

Allowed Time - 10 sec

Best time - 1.200

Why does storage write order matter for structs?

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#A

#B

#C

#D

Explanation:
Solidity packs struct variables tightly into storage slots based on declaration order. Reordering fields can change slot boundaries and break upgrade compatibility.

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Shubhada Pande
@ShubhadaJP • May 14, 2026

May 14, 2026
2.0K

Zero-Knowledge Cryptography Hub for Smart Contract Engineers

Zero-knowledge cryptography gets talked about like a prestige topic, but in real teams and real interviews, the gap is usually simpler than that. Many candidates can name ZK terms. Fewer...

Like 5 Replies 1
Difficulty - Medium

Total Plays - 1,593

Allowed Time - 10 sec

Best time - 0.784

What determines the base slot of a mapping?

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#A

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#D

Explanation:
The base slot of a mapping is derived using keccak256(key . slot). This hashing ensures unique storage locations per key without collisions.

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Priya Gupta
@CryptoSagePriya • Jan 1, 2026

Jan 1, 2026
1.8K

I’m starting my first smart contract job next week and I’m honestly nervous — what actually matters during probation?

I’m starting my first smart contract job next week and honestly I’m nervous.Everyone keeps saying “probation decides everything” but no one really explains how.Some people say move fast. Some say...

Like 6 Replies 9
Difficulty - Medium

Total Plays - 1,590

Allowed Time - 10 sec

Best time - 5.093

Which operation causes storage slot re-packing?

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#A

#B

#C

#D

Explanation:
Changing variable types alters how Solidity packs them into storage slots. This can shift offsets and corrupt existing storage layouts in upgradeable contracts.

Leaderboard
Difficulty - Medium

Total Plays - 49

Allowed Time - 10 sec

Best time - 1.638

Which data location is read-only by default?

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#A

#B

#C

#D

Explanation:
Calldata is immutable and cannot be modified by the callee. This makes it gas-efficient and safe for external function inputs

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Difficulty - Medium

Total Plays - 21

Allowed Time - 10 sec

Best time - 1.548 sec

What happens to storage slots after contract self-destruct?

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#A

#B

#C

#D

Explanation:
Storage is not automatically wiped when a contract self-destructs. The data remains on-chain and can be accessed again if a contract is redeployed at the same address.

Leaderboard
Difficulty - Medium

Total Plays - 24

Allowed Time - 10 sec

Best time - 1.455

Why is bytes32 cheaper than string in storage?

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#A

#B

#C

#D

Explanation:
bytes32 has a fixed 32-byte size and fits into a single storage slot. string is dynamically sized and requires additional storage pointers and length metadata.

Leaderboard
Difficulty - Medium

Total Plays - 24

Allowed Time - 10 sec

Best time - 3.228

Which operation resets a dynamic array length to zero?

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#A

#B

#C

#D

Explanation:
Using delete on a dynamic array sets its length to zero. Storage slots may remain allocated but become inaccessible through the array.

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Difficulty - Medium

Total Plays - 20

Allowed Time - 10 sec

Best time - 3.454

What does delete do to a mapping entry?

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#A

#B

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#D

Explanation:
Deleting a mapping key resets its value to the default type value. The key itself still exists conceptually since mappings do not track keys.

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Difficulty - Medium

Total Plays - 19

Allowed Time - 10 sec

Best time - 1.444

Which data location persists across transactions?

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#A

#B

#C

#D

Explanation:
Storage persists on-chain across transactions and blocks. Memory and calldata are temporary and cleared after execution completes.

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Vijay B
@xDhgFi3 • Dec 31, 2025

Dec 31, 2025
322

How would you approach breaking into protocol development as a final-year Solidity dev?

Hi everyone,I’m a final-year student and have been involved in Web3 since 2021. I spent close to two years interning with startups and am comfortable with Solidity (writing, debugging, and...

Like 2 Replies 4