Questions

True, the greenhouse effect is caused solely by human activities such as deforrestation, depletion of natural resources and emission of CO2 by using vehicles, refrigerators and AC's.

A computer has two types of memory.

1. Non-volatile and

2. Volatile.

Volatile memory is computer memory that requires power to maintain the stored information.

* It is a temporary memeory which cannot contain information permanently.

Example :: RAM or Random Access Memory

Non-volatile memory is computer memory that can retain the stored information even when not powered.

* It is a permanent memory in which data is stored in permanently.

Examples :: Hard disc, ROM, Floppy discs, Magnetic tape,...

A locked file can be accessed by only one user.

Data types are used for declaration of variables in computer programming languages. These determine the type and size of data associated with variables.

Data types examples - int, char, float, etc...

char datatype is the least storage data type with 1 byte.

int with 2 or 4 bytes.

float with 4 bytes

double with 8 bytes.

SQL statements are broadly classified into three. They are

1. DDL – Data Definition Language

DDL is used to define the structure that holds the data. For example, Create, Alter, Drop and Truncate table.

2. DML – Data Manipulation Language

DML is used for manipulation of the data itself. Typical operations are Insert, Delete, Update and retrieving the data from the table. The Select statement is considered as a limited version of the DML, since it can't change the data in the database. But it can perform operations on data retrieved from the DBMS, before the results are returned to the calling function.

3. DCL – Data Control Language

DCL is used to control the visibility of data like granting database access and set privileges to create tables, etc. Example - Grant, Revoke access permission to the user to access data in the database.

Radio waves have much longer wavelengths and lower frequencies than do visible light waves. In contrast, X-rays have much shorter wavelengths and higher frequencies. 

Ultraviolet Light (UV). part of the electromagnetic spectrum that consists of waves with frequencies higher than those of visible light and lower than those of x-rays.