I will mark you brainlist please help
1) A ball is thrown with the speed of 10 m/s from the 1st stair. The height of each stair is 10cm and the width is 15 cm. on which stair the ball will fall
Half life is defined as the time when the final concentration reduced to half of the initial value.
Thus, for first half life, the remaining percentage of the reactant is 50 percent that is 
Now, for second half life, the remaining percentage will be 50 percent of the remaining 50 percentage that is 
or 
Thus, general formula for n half lives =
Now, 98.4 years is equal to eighth times 12.3 years that is 
=
remaining material.
Therefore, mass of the nuclide will remain after 98.4 years= 
= 
Mass of remaining nuclide after 98.4 years =
1. The Precambrian is the earliest part of Earth's history, set before the current Phanerozoic Eon.
2.The Precambrian was originally defined as the era that predated the emergence of life in the Cambrian Period.
3. During the Precambrian era the earth started cooling and the outer edge of the planet solidified from molten lava to a solid crust. Water rained from the atmosphere and created oceans.
4. It is The first and longest subdivision of time for the earth.
5. The earth took form about 4.5 billion years ago. For the first 4 billion years of that time, the Earth was growing and changing.
6. he only multi-cellular life forms at the end of the Precambrian were in the oceans and included some groups that have survived until the present: jellyfishes and segmented worms.
7. The discovery of 3.85-billion-year-old marine sediments and pillow lavas in Greenland indicates the existence of liquid water and implies a surface temperature above 0 °C (32 °F) during the early part of Precambrian time.
8. The Precambrian encompasses the Archean and Proterozoic eons, which are formal geologic intervals that lasted from 4 billion to about 541 million years ago.
9. Precambrian rocks on most continents have revealed that additional primitive life-forms existed approximately 3.5 billion years ago.
10. The earliest evidence for the advent of life includes Precambrian microfossils that resemble algae, cysts of flagellates, tubes interpreted to be the remains of filamentous organisms, and stromatolites (sheetlike mats precipitated by communities of microorganisms).
Answer: A. It can be found on the periodic table. E. It is made of only one type of atom.
Explanation: Element is the pure substance which is made up of similar atoms and cannot be separated into its components. Example : Al
Compound is the pure substance which is made up by combination of two or more elements in a fixed ratio by mass. Example : 
A) Every element can be found on the periodic table.
B) Element can be a solid, liquid or a gas.
C) Elements can be separated into different components as it is made up of only single type of atoms.
D) Only solids have fixed shape and volume.
E) Elements are made up of only one type of atoms.
Answer:
Option a incompressible
Explanation:
Liquids have definite volume, but indefinite shape.
Liquids take the shape of the container . When a liquid is inside a container, it will take its shape. Unlike gases, a liquid cannot change its volume to spread out and completely fill a container. Hence a liquid cannot be compressed.
Immiscible is not right because this applies only when two liquids are there
Surfectants are compounds that reduce the surface tension between two liquids or a liquid or a gas, etc.
Hence here appropriate choice is
a) incompressible
