### R Online Test - MCQ Questions

Welcome to R Programming Online Test!. Here, we will present 35 MCQs (Multiple-Choice Questions) containing code snippets to test your coding and logical skills.

You can select the correct answer for each question and submit the test. You will get your online test score after finishing the complete test.

## 1. What is the primary function of the apply() function in R?

a) To execute a function over the margins of an array
b) To manipulate each element of a vector
c) To generate a sequence of numbers
d) To plot graphs

a) 10
b) 20
c) 30
d) 40

a) is.na(vec)
b) is.null(vec)
c) na.omit(vec)
d) null(vec)

d) open.csv()

## 5. What is the purpose of the set.seed() function in R?

a) To define the middle value of a dataset
b) To ensure the reproducibility of random number generation
c) To set the default directory
d) To establish a connection to a database

## 6. What will the following R code output?

a) 0 1 0 1
b) TRUE FALSE TRUE FALSE
c) 1 3
d) 2 4

## 7. How can you generate a sequence from 1 to 10 in R?

a) seq(1, 10)
b) sequence(1, 10)
c) 1:10
d) Both a) and c)

a) dplyr
b) ggplot2
c) tidyr
d) shiny

a) As characters
b) As factors
c) As numeric
d) As logical

## 10. What does the subset() function do in R?

a) Subtracts one number from another
b) Divides the dataset into train and test sets
c) Selects variables and observations based on conditions
d) Combines multiple data frames

a) NA
b) 12
c) 15
d) 0

## 12. How do you create a factorial function using recursion in R?

``````factorial <- function(n) {
if (n <= 1)
return(1)
else
return(n * factorial(n-1))
}
factorial(5)
``````
a) 120
b) 24
c) 5
d) None of the above

a) integer
b) double
c) character
d) logical

a) A vector
b) A list
c) An array
d) A data frame

## 15. What is the purpose of the rnorm() function in R?

a) To generate a sequence of numbers
b) To perform linear regression
c) To generate random numbers from a normal distribution
d) To normalize data

## 16. What is the output of the following R code?

``````x <- c(1, 2, 3, 4, 5)
print(sum(x))
``````
a) 15
b) 5
c) 10
d) 20

## 17. What will the following R code print?

``````x <- c(TRUE, FALSE, TRUE, FALSE)
print(length(x))
``````
a) 2
b) 4
c) TRUE
d) FALSE

## 18. What does the following R code output?

``````x <- 5
y <- 3
print(x %% y)
``````
a) 2
b) 1.67
c) 5
d) 3

## 19. What is the output of the following R code?

``````x <- seq(1, 5)
print(x[3])
``````
a) 1
b) 2
c) 3
d) 4

## 20. What does the following R code print?

``````vec <- c("apple", "banana", "cherry")
print(tolower(vec))
``````
a) "apple" "banana" "cherry"
b) "APPLE" "BANANA" "CHERRY"
c) "apple" "banana" "cherry"
d) None of the above

## 21. What will be the output of the following R code?

``````x <- c("a", "b", "c", "d")
print(paste(x, collapse = " "))
``````
a) "a b c d"
b) "abcd"
c) "a, b, c, d"
d) "a+b+c+d"

## 22. What does this R code output?

``````x <- c(10, 20, 30)
x <- append(x, c(40, 50))
print(x[5])
``````
a) 10
b) 20
c) 40
d) 50

## 23. What will the following R code snippet output?

``````x <- 5
if (x > 3) {
x <- 10
}
print(x)
``````
a) 5
b) 10
c) TRUE
d) FALSE

## 24. What does the following R code print?

``````x <- factor(c("high", "low", "medium", "high", "low"))
print(nlevels(x))
``````
a) 3
b) 5
c) 1
d) 2

## 25. What is the result of executing the following R code?

``````x <- c(1, 2, 3)
y <- c(4, 5, 6)
print(x * y)
``````
a) 4 10 18
b) 5 7 9
c) 1 2 3
d) 4 5 6

## 26. What will this R function output?

``````calculate <- function(a, b) {
return(a + b)
}
print(calculate(5, 3))
``````
a) 8
b) 15
c) 5
d) None of these

## 27. What is the output of the following R code?

``````x <- matrix(1:9, nrow=3)
print(x[2, 3])
``````
a) 2
b) 4
c) 6
d) 8

## 28. What is the output of this R program?

``````x <- c(TRUE, FALSE, TRUE, FALSE)
print(all(x))
``````
a) TRUE
b) FALSE
c) NULL
d) Error

## 29. What will the following R code snippet output?

``````x <- "Hello, R!"
print(substring(x, 8, 9))
``````
a) R!
b) R
c) o
d) Hello

## 30. What does this R code print?

``````x <- 1:10
print(x[x > 5])
``````
a) 1 2 3 4 5
b) 6 7 8 9 10
c) 5 6 7 8 9 10
d) 1 2 3 4

## 31. What is the outcome of the following R code?

``````x <- c("apple", "banana", "cherry")
print(length(x))
``````
a) 3
b) 6
c) 1
d) None of these

## 32. What does the following R code return?

``````x <- c(NA, 1, 2, NA, 3)
print(sum(x, na.rm = TRUE))
``````
a) NA
b) 6
c) 0
d) None of these

## 33. What is the result of executing the following R code?

``````x <- c("one", "two", "three")
y <- c("four", "five", "six")
print(c(x, y))
``````
a) "one" "two" "three" "four" "five" "six"
b) "one four" "two five" "three six"
c) "one" "four" "two" "five" "three" "six"
d) Error

## 34. What will the following R code snippet output?

``````x <- 10
if (x %% 2 == 0) {
print("Even")
} else {
print("Odd")
}
``````
a) Even
b) Odd
c) Error
d) None

## 35. What is the output of the following R code?

``````print(sqrt(16))
``````
a) 4
b) 16
c) 256
d) Error

## 36. What will be the output of the following R program?

``````x <- "100"
print(as.numeric(x) * 2)
``````
a) "200"
b) 200
c) Error
d) NULL