Name the method by which spirogyra reproduces under favourable conditions. Is this method sexual or asexual?
An object is placed at a distance of 30 cm in front of a convex mirror of focal length 15 cm. Write four characteristics of the image formed by the mirror.
What is sustainable management? Why is reuse considered better in comparison to recycle ?
Management of forest and wild life resources is a very challenging task. Why ? Give any two reasons.
Two carbon compounds X and Y have the molecular formula C4H8 and C5H12 respectively. Which one of these is most likely to show addition reaction? Justify your answer. Also, give the chemical equation to explain the process of addition reaction in this case.
Complete the following chemical equations:
(i) CH3COOC2H5+NaOH →
(ii) CH3COOH+NaOH →
(iii) C2H5OH+CH3COOH
Write the names given to the vertical columns and horizontal rows in the Modern Periodic Table. How does the metallic character of elements vary on moving down a vertical column? How does the size of atomic radius vary on moving left to right in a horizontal row? Give reason in support of your answer in the above two cases.
In the Modern Periodic Table, there are 18 vertical columns known as Groups and 7 horizontal rows known as Periods.
Metallic character increases down the group:
Reason: Ability to lose electrons increases on moving down the group due to
the increase in distance between the nucleus and the valence electrons and there is the decrease in the attraction between the nucleus and the valence electrons.
Atomic radius decreases left to right
Reason: the nuclear charge increases on moving from left to right across a period resulting in the increase in the attraction between the nucleus and the valence electrons.
An element P (atomic number 20) reacts with an element Q (atomic number 17) to form a compound. Answer the following questions giving the reason :
Write the position of P and Q in the Modern Periodic Table and the molecular formula of the compound formed when P reacts with Q.