Question Discussion & Solution

The correct answer is Sulphur.

• The sulphur is the eye irritating compound that is released when cutting onions.
• The syn-Propanethial-S-oxide is the chemical irritant produced by an onion.
• This chemical stimulates the eyes' lachrymal glands which release tears.
• Previously scientists used to blame enzyme alinase for the instability of substances in a cut onion.
• In 2002, a study in Japan proved that lachrymatory factor synthase is responsible for irritation of the eyes.

The correct answer is All of the above.

• Foreign Marriage Act,1969:
  • Section 4 of the act deals with the conditions relating to the solemnization of foreign marriages.

Key Points

• The act says that it solemnizes the marriage between parties one of whom which should be an Indian citizen under article 8 of the Indian Constitution or if the following conditions got satisfied:-
  • Spouse of both parties should not be living.
  • Both parties should be of sound mind.
  • At the time of marriage, the bridegroom should be of 21 years and the bride should be of 18 years.
  • Neither of the party is within the degree of prohibited relationship.
• With an element that personal law and custom laws governing at least one party permit marriage between them including that they are not within the degree of prohibited relationship.
• Section 5 of the act deals with the need for intended marriage.
• The section states that when a marriage is solemnized under this act the parties who got married have to give notice to the marriage officer of the district in writing specified in the First Schedule of the act.

The correct answer is ​CTRL + Z.

• CTRL + Z is used to undo changes (UNDO) in Ms-Word.

​Key Points

• CTRL + Z
  • To reverse the last action done by can be regained using CTRL+Z shortcut.
  • We can reverse more than one action using this shortcut tool.

Additional Information

• CTRL + Y
  • The keyboard shortcut for Redo is CTRL-Y.
• ​​Ctrl+N
  • ​​Ctrl+N is a keyboard shortcut most often used to create a new document, window, workbook, or other types of file.
• CTRL + H
  • Ctrl+H is a keyboard shortcut whose function varies depending on the program.
  • For example, with text editors, Ctrl+H is used to find and replace a character, word, or phrase.
  • In an Internet browser, Ctrl+H opens the history tool.

• Direct memory access (DMA) is a feature of computer systems that allows certain hardware subsystems to access main system memory (RAM), independent of the central processing unit (CPU)
• Disk drive is a hardware subsystem

Explanation:

• One of the most important contributors to the early construction of the periodic table was Russian scientist Dmitri Ivanovich Mendeléev.
• Mendeleev Periodic Table was introduced in 1869, following the rejection of Newlands Octave Law.
• Elements were arranged in Mendeleev's periodic chart according to their fundamental property, atomic mass, and chemical characteristics.
• Only 63 elements were known at Mendeleev's time.
• Mendeleev discovered that the properties of elements are the periodic function of their atomic mass in a periodic pattern after analysing their qualities.
• He ordered the elements in the periodic table so that those with comparable properties were in the same vertical columns.
• He developed a periodic law based on this finding, which states:- “The periodic function of an element's atomic mass is its property.”
• Demerits -  
  1. He couldn't find hydrogen in the periodic chart.
  2. Moving from one element to the next caused an irregular increase in atomic mass. As a result, the amount of elements that have yet to be identified is unpredictable.
  3. Isotopes were not considered. Later on, isotopes of elements that defied Mendeleev's periodic law were discovered.​ 

Additional Information

Mendeleev left places for undiscovered elements. 

• scandium, gallium and germanium, discovered later, have properties similar to Eka–boron, Eka–aluminium and Eka–silicon, respectively. So undiscovered elements were named also by Mendeleevs. 
• It was not very strictly based on increasing order of atomic mass.  For example, cobalt (atomic mass 58.9) appeared before nickel (atomic mass 58.7) based on periodic properties. 
• Noble gases can easily get adjusted in Mendeleev periodic table even they were discovered after the periodic table.