The correct answer is C. 60 to 65.
Silica is the main component of window glass, making up about 60 to 65% of its weight. The other main components are soda ash (Na2CO3) and lime (CaO). These three components are melted together at high temperatures to form a liquid glass. The liquid glass is then cooled and shaped into sheets of window glass.
Silica is a very important component of window glass because it gives the glass its strength and durability. It also helps to protect the glass from the elements, such as sunlight and rain.
Soda ash and lime are also important components of window glass, but they play different roles. Soda ash helps to lower the melting point of the glass, making it easier to work with. Lime helps to make the glass more durable and resistant to breaking.
The percentage of silica in window glass can vary depending on the type of glass being made. For example, float glass, which is the most common type of window glass, typically contains about 60 to 65% silica. However, other types of glass, such as tempered glass, can contain a higher or lower percentage of silica.
The percentage of silica in window glass is important because it affects the properties of the glass. For example, a higher percentage of silica will make the glass stronger and more durable, but it will also make the glass more difficult to work with.