Gastric juice in the stomach contains hydrochloric acid (HCl) which aids digestion and kills bacteria. Orange juice contains citric acid, vinegar acetic acid, milk lactic acid (from fermentation). The pH of stomach acid is around 1-2.
Explanation:
Dmitri Mendeleev proposed the periodic law based on atomic mass. However, anomalies arose. In 1913, Henry Moseley discovered that the atomic number (number of protons) is the fundamental property. He proposed the modern periodic law: the properties of elements are periodic functions of their atomic numbers.
Assertion (A): The first ionization energy of Nitrogen is higher than that of Oxygen. Reason (R): Nitrogen has a half-filled p-orbital which is exceptionally stable.
A.A is true but R is false.
B.Both A and R are true and R is the correct explanation of A.
C.A is false but R is true.
D.Both A and R are true but R is NOT the correct explanation of A.
Explanation:
Nitrogen (1s2 2s2 2p3) has a exactly half-filled p-subshell, which confers extra stability due to symmetry and exchange energy. Oxygen (1s2 2s2 2p4) has one paired electron in the p-orbital, leading to electron-electron repulsion, making it easier to remove. Thus, N has a higher IE than O. Both are true and R explains A.
Explanation:
Cetane number measures ignition quality of diesel fuel; higher cetane means easier ignition. Diesel has high cetane (40-55). Petrol has octane number. Methane is gas.
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