THE Hongkong Chinese Orchestra and the Yip's Children Choir will perform ''A Concert of Choral Delights'' from April 16 to 18 at the City Hall Concert Hall. The conductor of the concert, Dr Yip Wai-hong, said there would be children's singing and instrumental music, with emphasis on light, catchy melodies. The choir, accompanied by the Chinese orchestra, will sing a selection of Chinese and Western pieces including Yip Wai-hong's Joyful Childhood (premiere) and Children's March and Hebei folk songs Chinese Cabbage and Presenting Flowers . The violin ensemble of the children's choir will also play Haydn's Serenade and Romanian folk song Spring together with the orchestra. Presented by the Urban Council, the concert series will be held at 8 pm on April 16 and 17 and at 3 pm on April 18. Tickets ranging from $30 to $80 are available at all URBTIX outlets. For telephone reservation, call 7349009.