During sunset , you might have noticed that the western horizon becomes reddish . Why is it so ?

You know what thermoplastics and thermosetting plastics are. You might have noticed that those who collect old plastics do not accept certain type of plastic articles. What are they? What may be the reason for this ?

A sonometer wire of length 30 cm vibrates in the second overtone A violin string resonates in its fundamental frequency of 196hz .Where along the string must you place your finger so that the fundamental frequency becomes 440hz ,If the length of violin string is 40 cm .

You might have noticed the marking of 500 W on an electrical appliance . What does it indicate ?

Explain the reason for the following . At the time of sunset western horizon is seen red .

Explain i. Oxides of nitrogen have open chain structures while those of phosphorus have closed chain or cage structure. Why is it so? IIustrate with one structural example for each type of oxides or The oxides of phosphorus have cage strućtures but not open ones. ii. Elemental phosphorus does not exist as P_2 as N_2

You might have seen the twinkling of at night. But planets do not twinkle . Why ?