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The metallic oxide used in the form of powder in a paint is called a base

The base provides the paint with its body and bulk, giving it durability and opacity.

The sand is mixed with lime mortar to prevent shrinkage and cracking.

Adding sand to lime mortar helps to control the amount of shrinkage that occurs as the mortar dries and hardens, thereby reducing the risk of cracking

The type of brick suitable for panel walls in multi-storeyed buildings is either (a) or (b), meaning both hollow bricks and perforated bricks are suitable.

These types of bricks are lighter and provide better insulation, making them ideal for use in panel walls of multi-storeyed buildings.

The correct answer is none of the above.

All the statements provided are accurate:

1. Pan tiles are similar to pot tiles but are less curved.
2. Pan tiles are comparatively heavier, stronger, and more durable than curved tiles.
3. Fire bricks are generally used for lining kilns.

Thus, none of the statements are wrong.

The addition of pozzolana to Portland cement causes all of these:

1. Less heat of hydration: Pozzolana reduces the heat generated during the hydration process, which is beneficial for large concrete structures.
2. Increase in shrinkage: Pozzolana can lead to a slight increase in shrinkage compared to ordinary Portland cement.
3. Decrease in permeability: Pozzolana improves the density of the cement, reducing the permeability and enhancing durability.

So, the correct answer is all of these.

According to Indian standard specifications, the temperature for curing is 27°C.

This is the standard temperature typically maintained to ensure proper curing of concrete as per Indian standards.

The lime which contains more than 30% of clayey impurities in the form of silica, alumina, and iron oxide is known as hydraulic lime.

Hydraulic lime can set under water due to the presence of these impurities, which enable it to harden through chemical reactions with water.

Rich or fat lime:

• Slakes rapidly with considerable evolution of heat: Fat lime reacts quickly with water and generates a lot of heat during slaking.
• Takes a very long time to develop adequate strength: It has a slow setting time and takes a longer period to develop full strength.
• Has high plasticity: It has high workability and plasticity, making it easy to handle and shape.

So, the correct answer is all of these.

The main constituent of Portland cement is lime.

Lime, in the form of calcium oxide (CaO), is the primary ingredient in Portland cement, and it combines with other components like silica, alumina, and iron oxide to form the various compounds that give Portland cement its strength and durability.