43. A string of length L=0.75 mL is fixed at both ends and vibrates in a standing-wave pattern at a frequency of 100 Hz. A mass of 1.02 kg is attached to one end, providing the tension in the string. The standing-wave pattern shows three loops as shown on the right. Use g =9.8 m/s². What is the linear mass density of the string? oscillator L M (C) 4.0 × 10-3 kg/m (E) 8.0 × 10-2 kg/m (A) 8.0 x 10-4 kg/m (B) 1.6 × 10-3 kg/m (D) 2.0 x 10-2 kg/m

6. The basic building blocks of nucleic acids HC are nucleotides. The figure on the right shows a fragment of a nucleic acid structure. Which of the following statements is NOT correct? (A) DNA (deoxyribonucleic acid) and RNA (ribonucleic acid) contain the same nitrogenous bases, but their five-carbon sugars are different. H 0 -O -CH OH (B) A nitrogenous base condenses with a five-carbon sugar to form anucleoside; a nucleoside condenses with phosphoric acid to form a nucleotide; nucleotides undergo condensation polymerization to form a nucleic acid. (C) Under certain conditions, a nucleotide can react with both acids and bases. (D) In nucleic acid molecules, bases undergo complementary pairing through hydrogen bonding. (E) This nucleic acid fragment contains three chiral centers.

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