frogs,toads,snakes,lizards
 
        
             
        
        
        
Answer:
The factor that is tested is called the variable.
The variable is also what is changed in an experiment.
Hope this helped! :)
 
        
             
        
        
        
Answer:
The result of loss of topsoil are loss in fertility of soil, loss of water, crop production and hardened soil surface. Therefore, the correct answer to the above question is option A, B, C and D.  
Explanation:
When there is a loss of top layer of soil from the earth by any means, natural or artificial, it is known as soil erosion. The soil from one place gets detached and is transported to another area. Planting more and more trees is the one of the way to stop soil erosion as the roots of the plants hold the soil.  
When the soil from area is removed there is a loss of production in crop due to various reasons. The most fertile part of the soil occurs in the uppermost part.  Therefore, its removal has negative impact.  
 
        
             
        
        
        
A little trick i learnt: The atomic number reflects how many electrons there are, and there must be an equal charge. therefore, there are the same amount of protons as there are electrons. so if it has 81 protons, we look for number 81 in the periodic table, Thallium
        
             
        
        
        
The baby is used to getting what it needs through the placenta, which includes oxygen. The baby's lungs are initially filled with amniotic fluid.