Blockchain
1. The blockchain is a ---------------- of immutable records.
a. Decentralized distributed database
b. Centralized database
c. Relational Database
d. Spreadsheet
a
2. The technology was discovered with the invention of Bitcoins which is the ---------------
a. the first cryptocurrency
b. Second cryptocurrency
c. Third cryptocurrency
d. Fourth cryptocurrency
a
3. Concept of Ethereum
a. Bigdata
b. Machine Learning
c. Programming Language
d. Smart Contract
d
4. Concept of Bitcoin
a. Bigdata
b. Machine Learning
c. Programming Language
d. Cryptocurrency
d
5. Founder of Bitcoin
a. Satoshi Nakamoto
b. Santoshi Charli
c. Nakamoto Basco
d. Alexander
a
6. Founder of Ethereum
a. Alexander
b.Vitalik Buterin
c. Satoshi Nakamoto
d. Lara
b
7. Release Method of Bitcoin/Ethereum
a. Genesis Block Mined/Presale
b. Presale/Tokensale
c. Smartcontract/Cryptocurrency
d. Tokensale/Mining
a
8. Algorithm used Bitcoin/Ethereum
a. SHA256/Ethash
b. MD5/Bcrypt
c. Ethash/SHA256
d. MD5/SHA256
a
9.What is the principle on which blockchain technology is based on?
a. Distributed
b. Organizing
c. Planing
d. Coordinating
a
10. Distributed Network Means
a. There is no one central point of failure and also no single person can behave recklessly to damage the entire chain of network.
b. Allocation of resources, both hardware and software, to each individual workstation, or office location
a
11. Types of Blockchain
a. Public/Private/Consortium
b. Distributed/Decentralized/Trustless
a
12. Blocks in blockchain consist of ---------------
a. List of transaction records
b. Header
c. Payload
d. Message
a
13. Is it possible to modify the data once it is written in a block?
a. Yes
b. No
b
14. Blockchain is ----
a. online ledger
b. offline ledger
a
15. Block Identifiers in Blockchain can be identified by
a. the block header hash and the block height.
b. Payload and message
a
16. Each leaf node is a hash of a ----- of data, and each non-leaf node is a hash of its --- nodes.
a. Block / Child
b. Parent / Child
a
17. Datastructure used in blockchain
a. Merkle Tree
b. Hierarchial Tree
a
18. The amount of data cannot be larger than the ----
a. Blockchains address size
b. Block size
a
19. What is Hash?
a. A hash is a generated string, that is computed using our data is input.
b. Password
a
20. Traditional Database pros
a. Single point of failure
b. Controlled by one central authority
c. Missing Transparency
d. Cheap storage for large amounts of data
d
21. Where Blockchain really shines
a. Transparency
b. Data consistency
a
22. Common type of ledgers that can be considered by users in Blockchain
a. Decentralized Ledgers
b. Distributed Ledgers
c. Centralized Ledger
a,b,c
23. Decentralization
a. rely on a peer-to-peer network built on a community of users.
b. is an interconnected group of storage facilities and transportation systems that receive inventories of goods and then deliver them to customers.
A
24. Bitcoin is based on ________ blockchain?
a. Public
b. Private
c. Public Permissioned
d. Permissioned
a
25. ockchain can be stored as which of the following?
a. A flat file
b. A Database
c. Both of the above [Ans]
d.None of the above
26. In blockchain, blocks are linked ________?
a. Backward to the previous block [Ans]
b. Forward to next block
c. Not linked with each other
27. The primary benefit of immutability is…
a. Scalability
b. Improved Security
c. Tamper Proof
d. Increased Efficiency[Ans]
28. Hash identifying each block in the Blockchain is generated using which of the following cryptographic algorithm?
SHA128
SHA256 [Ans]
29. A block in the blockchain can never have more than one parent block?
True [Ans]
False
30. Blockchain forks can result in which of the following?
Multiple parent blocks
Multiple children blocks [Ans]
31. Which of the following is asymmetric encryption Algorithm?
Blowfish
Twofish
RSA [Ans]
Tripple DEA
32. Which is not a consenses algorithm
a. PBFT (Practical Byzantine Fault Tolerance)
b. Proof-of-work
c. Proof-of-stake
d. Tokenization
33. What is the value token for Ethereum?
a. ETH
b. ETC
a
34. What is the difference between Wei and Ether?
a. Wei is a denomination. 1 ETH = 10¹⁸ Wei
b. Wei is a denomination. 10 ETH = 10¹⁸ Wei
a
35. What is the average block time in Ethereum?
a. ~14 seconds
b. ~120 seconds
a
36.Does Ethereum support scripting? If so, what types of scripting?
a.Yes
b. No
a
37. What is the average block size in Ethereum?
a. Around 2KB, although it depends.
b. Around 2MB, although it depends.
A
38. Below are ways of getting Ethers? Find odd one out.
1. Become a miner
2. Trade other currencies
3. Foreign Exchange
4. Receive Ethers from others
39. Storage resides in ------------
a. Contract-state variables.
b. Functions
a
40. Memory, on the other hand, holds ------ items and ----- between function calls.
a. Permanent/ Cannot be Erased
b. Temporary/ can be Erased
b
41. ----- is a token standard that describes different functions and events that must be implemented in an Ethereum token contract.
a.ERC21
b.ERC20
b
42. The distinctive feature is that all ERC721 tokens are ------. An interface has to allow these tokens to be managed/owned/traded.
a. Unique
b. Immutable
a
44. Where do Ethers come from?
a. 60 million were first created in a presale in 2014. Also, ethers are created when a block is mined.
b. None of the above
a
45. ------ is essentially a computer, connected to the network, which processes transactions.
a. A Node
b. A Block
a
46.How many Ethereum networks are you familiar with?
a. 3
b. 10
a
47. What are some ways to interact with a Ethereum network?
a. Wallet or Dapp
b. Software or Webapp
48. Can you “hide” a transaction on a Ethereum network?
a.No
b.Yes
a
49. Where are transactions recorded?
a. Public Ledger
b. Notebook
a
50. What are the ids of Ethereum networks?
A: Live (id=1), Ropsten (id=3), Rinkeby (id=4), Private (assigned by the developer)
B: None of the Above
A
51. So I can mine some Ethers in Rinkeby and transfer them to Live network, right?
a. No
b. Yes
a
52. Why would you have a private network?
a. Because of data privacy, distributed database, permissions control and testing.
b. none of the above
a
53. How can you easily see details about transactions and blocks?
a. Etherscan.io
b. Ethereum.org
a
54. Etherscan is a --------------
a. Blockchain explorer
b. File explorer
a
55. The process of validating transactions (creating blocks) following a specific protocol (like Ethereum).
a. Consensus in blockchain
b. Transaction in blockchain
56. What are the two commonly used consensus models in blockchain?
a. Proof of work and proof of stake.
b. None of the above
a
57. It is essentially a puzzle which miners have to solve in order to generate proof of work and validate a transaction. It is computationally intensive.
a. Proof of Work
b. Proof of Stake
a
58. The creator of the block is chosen randomly by means of wealth and age. It is not computationally intensive.
a. Proof of Work
b. Proof of Stake
b
59.How can you mine Ethers?
a. Wallet
b. Currency
a
60. What is used to sign transactions?
a. Private Key
b. Public Key
a
61. Can you recover your Ethereum account after losing your private key?
a. Yes
b. No
a
62. How Can you recover your Ethereum account after losing your private key?
a. You can use your 12 word mnemonic
b. You can use your 18 word mnemonic
a
63. What are some ways to connect to a node?
a. IPC-RPC, JSON-RPC and WS-RPC
b. None of the above
a
64. So what is Geth?
a. Ethereum Cli client
b. Ethereum Network
a
65. You can connet to a geth client over the network using ------
a. JSON-RPC and WS-RPC
b. IPC-RPC and WS-RPC
a
66. Which RPC APIs are enabled by default?
a. eth, web3 and net.
b. None of the above
a
67. How would you enable admin api for JSON RPC?
a. By using the option — rpcapi
b. By using the option — rpc
68. What does — testnet do?
a. It connects the client to Ropsten network.
b. It connects the client to Tes network.
A
69. How would you load custom javascript files into your geth console?
a. By passing — preload and the path of the file.
b. By passing — load and the path of the file.
A
70. Where are geth client accounts stored?
a. In the keystore directory.
b. In the datastore directory.
A
71. ---- is the account which receives the mining awards, which is account with index 0.
a.ethercoinbase
b.etherbase
b
72. ----- refers to the amount of Ether you're willing to pay for every unit of gas, and is usually measured in “Gwei”.
a. Gas Price
b. Gas value
a
73. Example of a Smart Contract use case?
a. Seller and Buyer Scenario
b. Create dynamic content on fly
a
74.--------- is a tool which helps you to easily interact with the Ethereum networks in your browser
a. Metamask
b. Ethereum
a
75. What node does Metamask use?
a. infura.io
b. geth cli
a
76. What does Metamask NOT support?
a. Mining and contract deployment.
b. Interact with Dapps and Smart Contracts
a
77. Is execution of contracts free?
a. Yes
b. No
b
78. Is accessing a Smart Contract state free?
a. Yes
b. No
a
79. Is Querying state is a transaction.
a. No
b. Yes
a
80. Who executes the contracts?
a. Miner
b. Developer
a
81. How is transaction fee calculated?
a. Gas used * gas price
b. Ether value * gas price
a
82. Who pays for Smart Contracts invocation?
a.The user who invokes the contract.
b. Miner
a
83. What do nodes run Smart Contracts code on?
a. EVM
b. JVM
a
84. What does the EVM need in order to run a Smart Contract?
a. Contract’s bytecode
b. Solidity code
a
85. What are the segments of EVM on a higher level?
a. Memory area, Stacks and Execution engine
b. None of the above
a
86.An online tool for developing, testing and deloying contracts.
a. Remix
b. Infura
a
87. You can connect to a public node using ----
a. Metamask
b. Geth
c. Javascript
a
88. You can connect to local node using -----
a. Metamask
b. Geth
c. Javascript
b
89.You can connect to simulated memory node in the --------------------.
a. Metamask
b. Geth
c. Javascript
c
90. -----------is an app usually consists of a client which communicates to some centralized resources (owned by an organization).
a. DAPP
b. Web APP
a
91.Is the front end of a DApp restricted to any technology/framework?
A: No. You can use anything you want, like HTML, CSS, JS, Java, Python, the list goes on.
b. Yes. Solidity
a
92. What does the front end use in order to connect to the backend (Smart Contracts)?
a. Web3 API libraries.
b. Solidity
a
93. What do you need in order to interact with a contract from a DApp?
a. The contract’s ABI and bytecode.
b. Web3 API libraries
a
94. --- is a description of the public interface of a contract, which is used by DApps for invoking the contract.
a. ABI
b. Bytecode
a
95. The EVM on each node requires --------- in order to execute the contract code.
a. Bytecode
b. ABI
a
96. Why would you use BigNumber library?
a. Because Javascript does not handle big numbers correctly.
b. None of the above
a
97.How to list accounts in web3 1.x?
a. web3.eth.getAccounts
b. web3.getAccounts
a
98. ----- sends a transaction and costs money while.----- queries the state of the contract.
a. Send/Call
b. Sell/Buy
a
99. Is sending one ether like this “.send({ value: 1 })” okay?
a. No
b. Yes
a
100. util method web3.utils.toWei(1, ‘ether’) is used to send 1 ether then I have to mutiply the value by --------
a. 10^18
b. 10^16
a
101.The only function of web3.eth.sendTransaction() is to send ethers to a specific address, is that correct?
a. No
b. Yes
a
102. Do you know any solutions for scalability in Ethereum?
a. 2-layer protocols. Possible solutions are state channels and plasma.
b. None of the above
a
103. Is Solidity statically or dynamically typed?
a. It is statically typed
b. It is dynamically typed
104. What is the equivalent to the Java “Class” in Solidity?
a. Contract
b. Pragma
a
105. An instance of a contract is the deployed contract on the blockchain.
a. Instance
b. Method
a
106. Solidity supports multiple inheritance but doesn’t support --------
a. Overloading
b. Overriding
a
107. What is the very first thing you must specify in a Solidity file?
a. Version
b. Class
a
108. Contract consists mainly of storage variables, functions and ------.
a. Events
b. Methods
a
109. There is a constructor, fallback function, constant functions and functions that modify the -------
a. Contract state
b. Blockchain state
a
110. Is it perfectly fine to put multiple contract definitions into a single Solidity file?
a. yes
b. No
a
111. A contract can invoke, create and inherit from another contract(s).
a. ways in which two contracts can interact
b. ways in which contracts can invoked
a
112. What happens when you try to deploy a file with multiple contracts?
a.The compiler only deploys the last contract in that file and all other contracts are ignored.
b. The compiler only deploys the last contract in that file and all other contracts are not ignored.
A
113.What if I have a huge project, do I need to keep all my related contracts into a single file?
A. You can use import statement to import a file
B. You can use require statement to import a file
A
114. EVM is divided into Storage, Memory and ------
a. CallData
b.sendData
a
115. ----- is a key-value datastore (256 bit key & value). The read and write are more costly in terms of gas used per execution.
A. Storage
B. Memory
A
116. ------ is a temporary storage. The data is lost once the execution terminates. You can allocate complex datatypes like arrays and structs.
a. Memory
b. Storage
a
117. -------- can be thought of as the callstack. It is temporary, non-modifiable, and it stores EVM execution data.
a. callData
b. sendData
a
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