4Fe + 3O2 → 2Fe2O3 <or> The chemical formula for rust is Fe2O3. Rust is formed when iron reacts with oxygen in moist air. The following chemical equation represents the reaction: 4Fe + 3O2 → 2Fe2O3. Water is necessary for the oxidation reaction to occur and to facilitate transport of the electrons.
1) Answer: A hot pack feels warm when chemicals in it combine.
Explanation: Reactions or process in which heat is released(produced) are known as exothermic reactions or process and those in which the heat is absorbed are known as endothermic reactions or process.
If a beaker feels cools when chemical in it react then it means the chemicals have absorbed the heat energy from its surroundings and so it is an example of an endothermic process.
A hot pack feels warm when chemicals in it combine means the energy is released in the chemical reaction and so it is an example of an exothermic process.
Plants use the sun's energy for photosynthesis which is a process of forming food for the plants. Energy acts as a reactant in this process and so it is an example of endothermic process.
Frying an egg by heating it on a stove is an example of an endothermic process as the heat is required to fry the egg.
So, the only exothermic process is the second one, "A hot pack feels warm when chemicals in it combine."
2) In the given equation, heat is written as a product means the heat is released in the equation and so it is an example of an exothermic reaction.
So, the correct choice is the last one " It is exothermic because energy is released."
Answer:
Atomic number of this isotope = 77
Explanation:
Given that,
Mass number = 193
No of neutrons = 116
We need to find the atomic no of this isotope.
We know that,
Atomic mass = No of protons + No. of neutrons
Also, atomic no = no of protons
So,
Atomic mass = atomic no + No. of neutrons
⇒ Atomic no = Atomic mass - no of neutrons
Atomic no = 193 - 116
Atomic no = 77
Hence, 77 is the atomic no of the isotope.
<h2>Answer and Explanation </h2>
The body of water means the occurrence of water on earth’s surface. Examples are oceans, lakes, seas, ponds, and pools. The major bodies of water are:
- Pacific ocean is the biggest and deepest of Earth's oceanic divisions. It stretches from the Arctic Ocean in the direction to the Southern Ocean.
- Atlantic ocean is another giant of the world's oceans. It includes nearly 20 percent of the Earth's exterior and nearly 29 percent of its water covering space.
- The Indian Ocean is the third largest Ocean in the world. It is surrounded by Asia, Africa, and Australia.
- Arctic ocean is the smallest and shallowest of the world's five main oceans.
- Mediterranean sea is a sea is attached to the Atlantic Ocean.
Answer:
1.242 g/mL
Explanation:
Step 1: Given data
Mass of the empty container (m₁): 80.21 g
Mass of the filled container (m₂): 105.22 g
Volume of the unknown liquid (V): 20.14 mL
Step 2: Calculate the mass of the liquid
The mass of the liquid is equal to the difference between the mass of the filled container and the mass of the empty container.
Step 3: Calculate the density of the unknown liquid
The density of the liquid is equal to its mass divided by its volume.
