For a linear congruential algorithm

Xn+1 = 5 Xn mod 7

• Assume that X0 = 1, write out the sequence till a number is repeated in the sequence. Does this generate a full period? I think that this is 546231 and then it repeats, so I think its a full period? not sure.
• Using the keystream generated above (each key is 4 bits) for a stream cipher to encrypt the plaintext 3c 2f ab e4, what is the ciphertext?