2. Sample Papers
  3. KVPY

KVPY Sample Paper KVPY Stream-SX Model Paper-19

  • question_answer
    Which of the following metal salts gives a red and opaque borax bead in the reducing flame (in cold)?

    A) Ni

    B) Fe

    C) Cu       

    D) Mn

    Correct Answer: C

    Solution :

    \[N{{a}_{2}}{{B}_{4}}{{O}_{7}}\xrightarrow{\Delta }2NaB{{O}_{2}}+{{B}_{2}}{{O}_{3}}\]
    \[CuO+{{B}_{2}}{{O}_{3}}\xrightarrow{\Delta }Cu\,{{(B{{O}_{2}})}_{2}}\]
    \[2Cu\,{{(B{{O}_{2}})}_{2}}+4NaB{{O}_{2}}+2C\xrightarrow{\Delta }2Cu\]
    (red and opaque) \[+\,2N{{a}_{2}}{{B}_{4}}{{O}_{7}}+2CO\uparrow \]


You need to login to perform this action.
You will be redirected in 3 sec spinner