To determine the structure of ammonia (NH₃), we need to apply the Valence Shell Electron Pair Repulsion (VSEPR) theory. This theory helps predict the geometry of molecules based on the repulsion between electron pairs in the valence shell of the central atom.
D) Trigonal pyramidal geometry with bond angle 107° (less than tetrahedral 109.5° due to lone pair-bond pair repulsion); N-H bond length = 101.7 pm. This option accurately describes the molecular geometry, bond angle, and the reason for the deviation from ideal tetrahedral angle, along with the correct bond length for ammonia.
To determine the oxidation state of Nitrogen (N) in each oxide, we will use the general rule that the oxidation state of Oxygen (O) is typically -2 in most compounds. The sum of the oxidation states of all atoms in a neutral compound must be zero.
Comparing these calculated oxidation states with the given options, we find the correct match.
C) The calculated oxidation states are: N₂O: +1; NO: +2; N₂O₃: +3; NO₂: +4; N₂O₄: +4; N₂O₅: +5. This matches option C.
The question asks to identify the correct steps involved in the Ostwald process for the manufacture of nitric acid (HNO₃). This requires knowledge of the industrial chemical process.
The Ostwald process is an industrial method for producing nitric acid. It involves three main steps:
B) The steps listed in option B perfectly match the three main stages of the Ostwald process for nitric acid production: (i) catalytic oxidation of ammonia to nitric oxide, (ii) oxidation of nitric oxide to nitrogen dioxide, and (iii) absorption of nitrogen dioxide in water (with oxygen) to form nitric acid.
The question asks about the structure and properties of white phosphorus, one of the allotropic forms of phosphorus. We need to identify the option that accurately describes its molecular structure, bond angles, and physical characteristics.
B) Tetrahedral structure with 4 phosphorus atoms at the corners; P-P-P bond angle = 60° (highly strained); it is very reactive, soft, waxy solid. This option accurately describes the structure, bond angles, and key physical properties of white phosphorus. The tetrahedral arrangement leads to \(60^\circ\) bond angles, which are highly strained, making it very reactive. It is indeed a soft, waxy solid.
The question asks to identify the correct statement describing the differences between red phosphorus and white phosphorus. This requires knowledge of the allotropic forms of phosphorus and their distinct physical and chemical properties.
Red phosphorus is indeed a polymeric network solid, unlike white phosphorus which consists of discrete \(P_4\) molecules. Due to this polymeric structure, it has a much higher melting point (around 860 K, compared to ~317 K for white phosphorus). It is non-toxic, non-phosphorescent, insoluble in \(CS_2\), and significantly less reactive than white phosphorus. Its use in safety matchsticks is a well-known application, where it is part of the striking surface.
The question asks about the preparation methods for phosphine (\(\text{PH}_3\)). We need to evaluate each option based on known chemical reactions for phosphine synthesis.
B) Hydrolysis of calcium phosphide: \(\text{Ca}_3\text{P}_2 + 6\text{H}_2\text{O} \rightarrow 3\text{Ca}(\text{OH})_2 + 2\text{PH}_3\uparrow\), or by heating white phosphorus with \(\text{NaOH}\): \(\text{P}_4 + 4\text{NaOH} + 2\text{H}_2\text{O} \rightarrow 2\text{PH}_3 + 2\text{NaH}_2\text{PO}_2\). Both reactions listed in this option are well-established methods for the preparation of phosphine.