☑ MCQ PRACTICE

R Programming Unit 3

Practice objective questions for quick revision and examination preparation. Try answering each question before revealing the answer.

📚 R Programming

📖 Unit 3

🎯 MCQs

MCQ Practice

R Programming — Unit 3

Practice the following objective questions. Click “Show Answer” whenever you want to check your answer.

In R, which function is used to create a list?

A vector()

B list()

C array()

D create.list()

Correct Answer list()

Lists in R can contain elements of _____ types.

A Same

B Integer only

C Different

D Character only

Correct Answer Different

How do you access the second element of a list named mylist?

A mylist[2]

B mylist[[2]]

C mylist(2)

D mylist{2}

Correct Answer mylist[[2]]

Which operator is used to access list components by name?

A #

B @

C $

D %

Correct Answer $

To add an element to a list, it can be assigned to a _____.

A new index

B function

C vector type

D data frame

Correct Answer new index

What happens when NULL is assigned to a list element?

A The element becomes zero

B The element gets deleted

C The element becomes NA

D An error is generated

Correct Answer The element gets deleted

Which function is used to apply a function to each element of a list?

A apply()

B lapply()

C loop()

D each()

Correct Answer lapply()

What is the value of length(list()) in R?

A 0

B 1

C NULL

D Error

Correct Answer 0

Which function is used to find the size of a list?

A size()

B count()

C length()

D list.size()

Correct Answer length()

Which function gives the structure of a list?

A structure()

B str()

C typeof()

D inspect()

Correct Answer str()

Text concordance lists store _____.

A Numbers only

B Words and positions

C Images and files

D Functions and variables

Correct Answer Words and positions

Which statement deletes the second element of list x?

A x[2] <- 0

B delete(x[2])

C x[[2]] <- NULL

D remove(x, 2)

Correct Answer x[[2]] <- NULL

Which function reads a list from a file?

A read.list()

B scan()

C get.list()

D import.list()

Correct Answer scan()

What is the default indexing of a list in R?

A Name based

B Position based

C Value based

D Random

Correct Answer Position based

Which function is used to create a data frame in R?

A dataframe()

B data.frame()

C create.data()

D frame()

Correct Answer data.frame()

A data frame in R is most similar to a _____.

A Matrix

B Function

C String

D Scalar

Correct Answer Matrix

Each column of a data frame is a _____.

A Matrix

B Vector

C List only

D Function

Correct Answer Vector

Which operator is used to access a data-frame column by name?

A #

B $

C %

D @

Correct Answer $

What is the data type returned by class(df) for a data frame df?

A matrix

B vector

C data.frame

D list

Correct Answer data.frame

Which function returns the number of rows and columns of a data frame?

A size()

B length()

C dim()

D shape()

Correct Answer dim()

Which function displays the first few rows of a data frame?

A first()

B head()

C top()

D rows()

Correct Answer head()

What does df[,2] return when df is a data frame?

A First column

B Second row

C Second column

D Entire data frame

Correct Answer Second column

Which statement adds a new column to a data frame?

A df + newcol

B df$newcol <- vector

C add(df, newcol)

D df.column(newcol)

Correct Answer df$newcol <- vector

A column can be removed from a data frame by assigning _____ to it.

A 0

B NA

C NULL

D FALSE

Correct Answer NULL

Which function applies a function across rows or columns of a data structure?

A apply()

B lapply()

C rowapply()

D column()

Correct Answer apply()

Which function is used to transpose a matrix or data frame?

A transpose()

B t()

C trans()

D rotate()

Correct Answer t()

Which function combines data frames vertically?

A cbind()

B merge()

C rbind()

D combine()

Correct Answer rbind()

Which function merges data frames using common columns?

A join()

B merge()

C combine()

D match.data()

Correct Answer merge()

True / False

R Programming — Unit 3

Check whether the following statements are True or False.

Lists can contain another list inside.

Answer TRUE

All columns in a data frame must be of the same type.

Answer FALSE

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