# IBM Core CS Questions with Answers

8 previously-asked core cs questions from IBM's hiring process, each with the correct answer and a worked explanation. Written against the company's actual test pattern.

_Source: Astra (https://useastra.in). Updated 2026-09-05._

### 1. Which language is widely used for data science and artificial intelligence?

A. Python
B. HTML
C. CSS
D. Assembly

**Answer:** Python

**Explanation:** Python has rich libraries (NumPy, pandas, scikit-learn, TensorFlow) that make it popular for data science and AI.

### 2. What does the cloud term SaaS stand for?

A. Software as a Service
B. System as a Service
C. Storage as a Service
D. Server as a Service

**Answer:** Software as a Service

**Explanation:** SaaS delivers software over the internet on a subscription basis, such as Gmail or Salesforce.

### 3. Which SQL command is used to retrieve data from a table?

A. SELECT
B. INSERT
C. UPDATE
D. DELETE

**Answer:** SELECT

**Explanation:** SELECT queries and returns rows from one or more tables.

### 4. Which OOP relationship represents an is-a association?

A. Inheritance
B. Composition
C. Aggregation
D. Association

**Answer:** Inheritance

**Explanation:** Inheritance models an is-a relationship, where a subclass is a kind of its superclass.

### 5. Which of the following is a supervised machine learning task?

A. Classification
B. Clustering
C. Association rule mining
D. Dimensionality reduction

**Answer:** Classification

**Explanation:** Classification learns from labelled data to predict categories, which is supervised learning; clustering is unsupervised.

### 6. What is the time complexity of linear search?

A. O(n)
B. O(1)
C. O(log n)
D. O(n^2)

**Answer:** O(n)

**Explanation:** Linear search may examine every element, so it is O(n).

### 7. What does multitasking mean in an operating system?

A. Running multiple tasks apparently at the same time
B. Using multiple monitors
C. Having many files open
D. Backing up data

**Answer:** Running multiple tasks apparently at the same time

**Explanation:** Multitasking lets the OS switch rapidly between processes so they appear to run simultaneously.

### 8. What does URL stand for?

A. Uniform Resource Locator
B. Universal Reference Link
C. Unified Resource Label
D. User Resource Locator

**Answer:** Uniform Resource Locator

**Explanation:** A URL (Uniform Resource Locator) is the address of a resource on the web.

More IBM preparation, including the full recruitment process: https://useastra.in/campus/ibm