Test: Study Of The First Element – Hydrogen - Class 9 MCQ

Hydrogen is the lightest gas known, with a lower density than air. This property allows hydrogen-filled balloons to rise in the atmosphere. It is also highly reactive, making it significant in various chemical processes.

When hydrogen burns in oxygen, it reacts to form water (H2O). This reaction is highly exothermic and releases energy. The combustion of hydrogen is characterized by a 'pop' sound, indicating the rapid production of water vapor.

The reaction of water with gold does not produce hydrogen because gold is a noble metal that does not react with water. In contrast, potassium, sodium, and calcium are highly reactive metals that can liberate hydrogen when reacted with water.

Hydrogen has an atomic number of 1, indicating it is the first element in the periodic table. It is located in Group IA (alkali metals) and the 1st Period. This unique position reflects its single electron in the valence shell, which contributes to its chemical properties.

Burning hydrogen in an oxygen-rich environment primarily results in the formation of water vapor (H2O) and the release of a significant amount of energy. This reaction is exothermic and is utilized in various applications, including rocket propulsion and fuel cells.

Unlike alkali metal oxides, which are basic, and halogen oxides, which tend to be acidic, hydrogen's oxide (H2O) is neutral. This property highlights hydrogen's unique position in the periodic table, as it does not fully align with the behavior of either alkali metals or halogens.

Alkali metals react with hydrogen to form hydrides, which are compounds containing hydrogen and a metal. For example, sodium reacts with hydrogen to form sodium hydride (NaH). This reaction highlights the ability of alkali metals to form stable compounds with hydrogen.

Henry Cavendish discovered hydrogen in 1766 and initially referred to it as "inflammable air" due to its flammability. Later, Antoine Lavoisier named it "hydrogen," which means "water former," highlighting its role in producing water during combustion.

The Haber Process is the industrial method employed for synthesizing ammonia from nitrogen and hydrogen gases. This process is crucial for producing fertilizers and involves the reaction of nitrogen gas with hydrogen under high pressure and temperature in the presence of a catalyst.

In the reaction of zinc with hydrochloric acid, zinc is oxidized while hydrogen ions are reduced to form hydrogen gas. This exemplifies hydrogen's role as a reducing agent, as it facilitates the reduction of metal ions in the process.

Palladium is known for its ability to adsorb hydrogen gas. In fact, it can absorb more than 900 times its own volume of hydrogen, making it useful in various applications, including catalysis and hydrogen storage technologies.

The reaction CuO + H2 → Cu + H2O exemplifies hydrogen acting as a reducing agent, where it reduces copper(II) oxide (CuO) to copper (Cu) while being oxidized to water. This demonstrates hydrogen’s effectiveness in reducing metal oxides.

The activity series ranks metals based on their reactivity, specifically their ability to displace hydrogen from water or acids. Metals above hydrogen in the series can displace it, while those below cannot, which is crucial for understanding hydrogen production and chemical reactions.

Hydrogen, when mixed with oxygen, can create an explosive mixture. If the mixture is ignited, it can result in a violent explosion, particularly if the proportions are not ideal. This property is significant when handling hydrogen in industrial applications.

Hydrogen is produced when reactive metals like potassium or sodium react with cold water. This reaction is highly exothermic and results in the formation of hydroxides and hydrogen gas. For example, when sodium reacts with water, it forms sodium hydroxide and hydrogen gas, which burns with a yellow flame.

Copper does not displace hydrogen from dilute acids because it is below hydrogen in the reactivity series. Metals like zinc and magnesium can displace hydrogen, while copper, being less reactive, cannot engage in such reactions effectively.

Iron is a metal, not a non-metal; therefore, it does not belong in the same category as sulfur, chlorine, and oxygen, which are non-metals that can react with hydrogen to form various compounds, such as H2S, HCl, and H2O, respectively.

The Bosch Process is characterized by passing steam over hot carbon (coke) to produce hydrogen and carbon monoxide, a process that plays a vital role in industrial hydrogen production. This method is efficient and widely used for generating hydrogen on a large scale.

In the petroleum industry, hydrogen is primarily used for the hydrogenation of oils, which involves converting liquid vegetable oils into solid fats. This process is essential for producing margarine and other food products and involves the use of catalysts under high pressure.

Hydrogen is considered a clean fuel primarily because when it burns, it reacts with oxygen to produce only water as a byproduct. This feature makes it an environmentally friendly alternative to fossil fuels, which emit carbon dioxide and other pollutants upon combustion.