Answers for "Which of the following is the command to replace a value in a data frame at "third" row of column "Name" with a NAN value ?"

pandas replace null values with values from another column

#Python
#Col 1 = where you want the values replaced
#Col 2 = where you want to take the values from
df["Col 1"].fillna(df["Col 2"], inplace=True)

replace na in a column with values from another df

library(dplyr)

df1 %>% inner_join(df2, by= "ID") %>%
  mutate(Count = coalesce(Count.x, Count.y)) %>%
  select(ID, Count)

#   ID Count
# 1 11   345
# 2 22   456
# 3 33   786
# 4 44   765
# 5 55   890
# 6 66   888
# 7 77   654